building qemu with msys2 mingw64 in github actions, sed error unterminated address regex
Description of problem:
in Github Actions (Windows)
```
$ make --trace -j $(nproc)
ninja: no work to do.
/d/a/qemu_app/qemu_app/qemu/BUILD/pyvenv/bin/meson introspect --targets --tests --benchmarks | D:/a/qemu_app/qemu_app/qemu/BUILD/pyvenv/bin/python3.exe -B scripts/mtest2make.py > Makefile.mtest
D:\a\_temp\msys64\mingw64\bin\sed.exe: -e expression #1, char 41: unterminated address regex
D:\a\_temp\msys64\mingw64\bin\sed.exe: -e expression #1, char 41: unterminated address regex
```
Steps to reproduce:
```sh
# enable symlinks in msys2 MINGW64 shell

export MSYS=winsymlinks:native

# download and extract qemu

curl -L https://download.qemu.org/qemu-9.0.0-rc4.tar.xz -O
tar xvJf qemu-9.0.0-rc4.tar.xz
mv qemu-9.0.0-rc4 qemu

# remove symlinks known to cause `git add` to fail, we will recreate these later in the yaml file

/usr/bin/rm -f qemu/roms/edk2/EmulatorPkg/Unix/Host/X11IncludeHack
/usr/bin/rm -f qemu/roms/skiboot/opal-ci/build-debian-unstable.sh
/usr/bin/rm -f qemu/roms/skiboot/opal-ci/build-fedora-rawhide.sh
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynq/zynq-cse-nand
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/avnet-ultra96-rev1
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-g-a2197-00-revA
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-m-a2197-01-revA
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-m-a2197-03-revA
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-mini
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-mini-emmc0
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-mini-emmc1
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-mini-qspi
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-p-a2197-00-revA
/usr/bin/rm -f qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-zcu104-revC
/usr/bin/rm -f qemu/roms/u-boot/include/ctype.h
/usr/bin/rm -f qemu/roms/u-boot/tools/binman/binman
/usr/bin/rm -f qemu/roms/u-boot/tools/dtoc/dtoc
/usr/bin/rm -f qemu/roms/u-boot/tools/microcode-tool
/usr/bin/rm -f qemu/roms/u-boot/tools/patman/patman
/usr/bin/rm -f qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/almalinux-8-prep.sh
/usr/bin/rm -f qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/alpine-317-prep.sh
/usr/bin/rm -f qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/alpine-edge-prep.sh
/usr/bin/rm -f qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/fedora-37-prep.sh
/usr/bin/rm -f qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/fedora-38-prep.sh
/usr/bin/rm -f qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/fedora-rawhide-prep.sh

# push qemu to github to test

git init
git add -Av
git commit -m "qemu fail"
git branch -M main

git remote add origin < a url to a newly created git repo to test the qemu build which currently fails with sed error >

git push origin
```
```yaml

# save this in the following file: .github/workflows/windows.yaml

# Job execution time - Each job in a workflow can run for up to 6 hours of execution time.
# Workflow run time - Each workflow run is limited to 35 days

name: windows

on:
  push:
    branches: [ "main" ]
  workflow_dispatch:

defaults:
  run:
    shell: msys2 {0}

# each job runs under a NEW image
jobs:
  build_qemu:
    strategy:
      matrix:
        include:
          - os: windows-latest
            name: windows
            sys: MINGW64

    runs-on: ${{ matrix.os }}

    name: build qemu - ${{ matrix.name }}

    steps:
      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
      - uses: actions/checkout@v4
        with:
          ref: ${{needs.should_run.outputs.output1}}
          submodules: recursive

      - name: '${{ matrix.icon }} Setup MSYS2'
        uses: msys2/setup-msys2@v2
        with:
          msystem: ${{matrix.sys}}
          update: true
          path-type: strict

      - name: update packages
        run: |
          pacman -Sy

      - name: install qemu deps
        run: |
          # https://github.com/qemu/qemu/blob/master/.gitlab-ci.d/windows.yml#L84
          pacman -S --noconfirm --needed pactoys
          pacman -S --noconfirm --needed bison flex git
          pacboy -S --noconfirm --needed make:p cmake:p gcc:p meson:p autotools:p ninja:p python:p python-sphinx:p python-sphinx_rtd_theme:p tools-git:p angleproject:p capstone:p curl:p cyrus-sasl:p dtc:p expat:p fontconfig:p freetype:p fribidi:p gcc-libs:p gdk-pixbuf2:p gettext:p glib2:p gmp:p gnutls:p graphite2:p gst-plugins-base:p gstreamer:p gtk3:p harfbuzz:p jbigkit:p lerc:p libc++:p libdatrie:p libdeflate:p libepoxy:p libffi:p libiconv:p libidn2:p libjpeg-turbo:p libnfs:p libpng:p libpsl:p libslirp:p libssh:p libssh2:p libtasn1:p libthai:p libtiff:p libunistring:p libunwind:p libusb:p libwebp:p libwinpthread-git:p lz4:p lzo2:p nettle:p openssl:p opus:p orc:p p11-kit:p pango:p pixman:p SDL2:p SDL2_image:p snappy:p spice:p usbredir:p xz:p zlib:p zstd:p brotli:p bzip2:p nghttp2 diffutils grep make sed:p binutils:p capstone:p curl:p cyrus-sasl:p dtc:p gcc:p glib2:p gnutls:p gtk3:p libgcrypt:p libjpeg-turbo:p libnfs:p libpng:p libssh:p libtasn1:p libusb:p lzo2:p nettle:p ninja:p pixman:p pkgconf:p python:p SDL2:p SDL2_image:p snappy:p spice:p usbredir:p zstd:p

      - name: restore symlinks
        run: |
          export MSYS=winsymlinks:native
          ln -s /opt/X11/include qemu/roms/edk2/EmulatorPkg/Unix/Host/X11IncludeHack
          ln -s build-ubuntu-latest.sh qemu/roms/skiboot/opal-ci/build-debian-unstable.sh
          ln -s build-fedora33.sh qemu/roms/skiboot/opal-ci/build-fedora-rawhide.sh
          ln -s zynq-zc770-xm011 qemu/roms/u-boot/board/xilinx/zynq/zynq-cse-nand
          ln -s zynqmp-zcu100-revC qemu/roms/u-boot/board/xilinx/zynqmp/avnet-ultra96-rev1
          ln -s zynqmp-a2197-revA qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-g-a2197-00-revA
          ln -s zynqmp-a2197-revA qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-m-a2197-01-revA
          ln -s zynqmp-a2197-revA qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-m-a2197-03-revA
          ln -s zynqmp-zcu102-rev1.0 qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-mini
          ln -s zynqmp-zcu100-revC qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-mini-emmc0
          ln -s zynqmp-zcu102-rev1.0 qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-mini-emmc1
          ln -s zynqmp-zcu102-rev1.0 qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-mini-qspi
          ln -s zynqmp-a2197-revA qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-p-a2197-00-revA
          ln -s zynqmp-zcu104-revA qemu/roms/u-boot/board/xilinx/zynqmp/zynqmp-zcu104-revC
          ln -s linux/ctype.h qemu/roms/u-boot/include/ctype.h
          ln -s main.py qemu/roms/u-boot/tools/binman/binman
          ln -s main.py qemu/roms/u-boot/tools/dtoc/dtoc
          ln -s microcode-tool.py qemu/roms/u-boot/tools/microcode-tool
          ln -s main.py qemu/roms/u-boot/tools/patman/patman
          ln -s centos-stream-8-prep.sh qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/almalinux-8-prep.sh
          ln -s alpine-prep.sh qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/alpine-317-prep.sh
          ln -s alpine-prep.sh qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/alpine-edge-prep.sh
          ln -s fedora-prep.sh qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/fedora-37-prep.sh
          ln -s fedora-prep.sh qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/fedora-38-prep.sh
          ln -s fedora-prep.sh qemu/tests/lcitool/libvirt-ci/ci/gitlab/all_mappings_prep_env/fedora-rawhide-prep.sh

      # we dont use split.exe since we need only fails the build and need not upload the results

      # there is no use in caching the build directory since ../configure will cause a full rebuild
      # and we are lazy to detect an existing Makefile

      - name: cmake configure qemu - Release
        run: |
          export MSYS=winsymlinks:native
          cd qemu
          mkdir BUILD || true
          mkdir BUILD/BUILD_ROOT || true
          cd BUILD
          ls -l

          # this should succeed
          ../configure --prefix=$(pwd)/BUILD_ROOT --enable-sdl --enable-gtk --disable-user --target-list=x86_64-softmmu --enable-whpx

      - name: cmake build qemu - Release
        run: |
          export MSYS=winsymlinks:native
          cd qemu/BUILD
          ls -l
          cat -n Makefile

          # this should fail with sed.exe: -e expression #1, char 41: unterminated address regex
          make --trace -j $(nproc)
```
Additional information:
https://github.com/mgood7123/qemu_app/actions/runs/8732163169/job/23958798258

note `make` `succeeds` (returns 0) but does not build anything due to sed error

qemu folder is https://download.qemu.org/qemu-9.0.0-rc4.tar.xz

symlinks incompatible with `git add` have been removed and then recreated in GHA