[PATCH v3] include: Add some math declarations.

[Daniel Lehman]

> In file included from ../wine/dlls/msvcrt/math.c:45:
> ../wine/include/msvcrt/math.h:117:28: note: previous declaration of ‘llroundf’ with type ‘long long int(float)’
> make: *** [Makefile:104865: dlls/msvcr120/math.o] Error 1

i didn't see those with mingw/llvm (although there are a ton of
warnings without my changes)

but i tried with gcc and without-mingw and do see those errors.  i'll
send another version

thanks
daniel