Buildbot core not showing GIT_VERSION in library version and performance difference compared to self-built core

[Ryunam]

With PR #5 I have implemented the visualization of the commit hash for the library version string in libretro.cpp, in addition to the emulator version itself which is currently hard-coded to 115.

When bsnes-libretro is compiled locally on my Windows system with MSYS2/Mingw64, this works well and the commit information is reported correctly in RetroArch:

However the same core downloaded from the buildbot does not seem to show the commit hash. Only the emulator version is displayed:

There is also a performance difference: using fast-forward, the buildbot version seems to be at least 20-30fps faster on average than the one compiled locally with Mingw on Windows.