Segfault when saving VM snapshot via QEMU monitor on MIPS and MIPSEL
Description of problem:
When entering the QEMU monitor using Ctrl-A then C, and running the savevm QEMU command, the emulator hangs for a while and then exits with a segfault. This occurs on MIPS and MIPSEL system emulators using the same command line arguments. ARM32, aarch64 and x86_64 emulators don't seem to have this problem. I haven't tested it on any other architectures as I don't have kernel or drive images for them. `qemu-img` seems to work fine with the QCOW2 images used for this test, I was able to create and load offline snapshots from them. The images were created from raw EXT2 filesystem images produced by Buildroot, using `qemu-img convert`.
Steps to reproduce:
1. Start the QEMU system emulator for MIPS/MIPSEL with the given command line.
2. Enter the QEMU monitor with Ctrl-A, C.
3. Run `savevm <vm name>`.
Additional information:
I tried logging what QEMU was doing with the `-D ./log.txt` command line option, but the produced log file was empty.

If you need me to send you the kernel image files and QCOW2 images used, I would be happy to do so.