The -ffast-math gcc option implies the -ffinite-math-only option, which
produces wrong results with Inf and NaN. Use integer math to detect the
sign of float numbers in FTRC to avoid these issues.
Also the upper cut off value for conversion was apparently wrong.
Also fixed the x86 dynarec but not tested.
Fixes wrong car color in Tokyo Xtreme Racer car selection screen.
This consolidates some of the work done for TARGET_NO_NVMEM and
feat/no-direct-memmap. If nvmem is disabled at compile time or alloc
fails _nvmem_enabled() will return false. Various other fixes
and cleanups all around.
Flyinghead