Issue building on Manjaro Arm64
Hey there, was trying to build this on Manjaro Arm64 but ran into this issue

```
[corey@corey-pi4 Build]$ CC=clang CXX=clang++ cmake -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=Release -DENABLE_LTO=True -DBUILD_TESTS=False -G Ninja ..
-- Checking for module 'libxxhash>=0.7.3'
--   Package dependency requirement 'libxxhash >= 0.7.3' could not be satisfied.
Package 'libxxhash' has version '', required version is '>= 0.7.3'
CMake Error at /usr/share/cmake-3.20/Modules/FindPkgConfig.cmake:556 (message):
  A required package was not found
Call Stack (most recent call first):
  /usr/share/cmake-3.20/Modules/FindPkgConfig.cmake:778 (_pkg_check_modules_internal)
  CMakeLists.txt:108 (pkg_check_modules)


-- Configuring incomplete, errors occurred!
See also "/run/media/corey/47F22DEE70C10570/projects/FEX/Build/CMakeFiles/CMakeOutput.log".
```

I installed xxhash but it still thinks it's missing.