mingw-w64 build failure

[Richard Copley]

As of this[1] revision of the mingw-w64 headers, building "w32image.o"
fails with error:

In file included from w32image.c:32:
w32common.h:45:3: error: expected identifier before numeric constant
   45 |   OS_NT
      |   ^~~~~

OS_NT is defined to 1 in "shlwapi.h", condtional on
!defined(NO_SHLWAPI_ISOS).

[1] 
<https://sourceforge.net/p/mingw-w64/mingw-w64/ci/dc7ef298837d4581200a3bed660aed36818c1b00/>