Make FPUD_REMAINDER/COMPARE/EXAMINE portable to x86_64
Make FPUD_LOAD_CONST portable to x86_64
Make FPUD_TRIG/SINCOS portable to x86_64
Make FPUD_XTRACT portable to x86_64
Make FPUD_WITH_POP portable to x86_64
Make FPUD_PTAN portable to x86_64
Make FPUD_FYL2X portable to x86_64
Enable fpu-x86 on x86_64 too
Make exc_mask/fclex a bit more consistent
Allow gcc to use ax for fnstsw where possible