GTK3, system SDL2 (pkg-config), Linux link libraries, linker groups,
and _GLIBCXX_DEBUG were in the generic non-MSVC branch, breaking
cmake configure on non-Linux POSIX platforms.
zstd ships a hand-written huf_decompress_amd64.S that was being
disabled on all non-MSVC builds. New behavior matches zstd's own
CMakeLists which enables it on GCC/Clang x86_64 and disables it
on MSVC and non-x86 architectures.
PCLMULQDQ CRC folding is excluded for now due to a runtime hang on
Linux — needs further investigation. The library does runtime feature
detection so all other paths should be safe on CPUs without these extensions.
Based entirely off existing xbyak x86 implementation and available
tests. Still needs a lot of optimization and testing on non-Windows
platforms.
So far passes all tests and boots at least some games on Windows.
