The asm code cannot currently be used with tcc since tcc doesn't support 't'
constraint.
Use inline C implementation instead, place it win32/include/tcc/tcc_libm.h, and
include it from win32/include/math.h.
Since fpclassify now works, it also fixes few other macros which depend on it.
Implicitly fixed: isfinite, isinf, isnan, isnormal.
The implementations were taken from musl-libc rs-1.0 (MIT license).
musl-libc: http://git.musl-libc.org/cgit/musl/tree/src/math?h=rs-1.0
license: http://git.musl-libc.org/cgit/musl/tree/COPYRIGHT?h=rs-1.0
It was broken due to tcc not able to compile asm with 't' constraint, and it's
still broken because fpclassify on which it now depends has the same issue. Next
commit will fix this.