Add support for JIT on UWP
orc: Implement a windows helper for getenv() On Windows, getenv() is deprecated and does not work in all cases. On the Universal Windows Platform (UWP) it always returns NULL. Add a wrapper orc_getenv() that calls GetEnvironmentVariable on Windows. Also change semantics to always make a copy before returning.
orccodemem: Add support for Universal Windows Platform apps VirtualAlloc is VirtualAllocFromApp when targeting UWP, and you can only allocate executable pages if you have the codeGeneration capability set in the app manifest. Check for that capability in _orc_compiler_init() and switch to backup code or emulation if it isn't available instead of crashing when VirtualAllocFromApp returns NULL. Also you cannot allocate pages that are both READWRITE and EXECUTE, so we allocate as read-write first, then set the memory as execute-only after the code has been compiled and copied over.
orc: Fix some warnings on MSVC and enable --werror
ci: Attempt to fix broken Windows CI https://gitlab.freedesktop.org/nirbheek/orc/-/pipelines/169274 Update to latest image and use the gstreamer runner tag. Matches the gst-ci template. Also try to make MSYS2 CI more resilient by following: https://github.com/msys2/setup-msys2/blob/master/main.js#L98