check if the cpu supports the impl before saying it's available
fixes so it will compile and run under mingw
* use cdecl instead of stdcall to avoid _name@16 issues
* generate both _name and name for asm functions
* use asm_calling_convention for function pointers that point to asm routines instead of STDCALL
* use aret(n) instead of a1(ret n) to return from potential stdcall'd functions under 32bit
* remove need for ssse3_rotl8/16_32bit in inline asm (_name vs name, constants had to be static for asm visibility)
* put a pause in to account for shell scripts running too fast? under mingw