Remove unneeded -Defines in the compiler command line (MinGW and MSVC).

Remove unneeded -Defines in the compiler command line (MinGW and MSVC).

* nt/nmake.defs:
* nt/gmake.defs (FONT_CFLAGS): Remove.
(EMACS_EXTRA_C_FLAGS): Don't include FONT_CFLAGS.
(CFLAGS): Don't include WIN32_LEAN_AND_MEAN, _WIN32_WINNT, -D$(ARCH)
and _CRTAPI1.
(ARCH_FLAGS): Don't include _X86_.

* nt/config.nt (_WIN32_WINNT, WIN32_LEAN_AND_MEAN): Define.

* src/makefile.w32-in (LOCAL_FLAGS):
Don't include WINDOWSNT, DOS_NT and _UCHAR_T.

* src/sysdep.c (_spawnlp, _getpid):
Declare with explicit _cdecl instead of _CRTAPI1.

* src/editfns.c (Fget_internal_run_time):
Check for WINDOWSNT with #ifdef, not #if.