The MSVCRT runtime as used on Windows does not support %zu, but instead recommends %Iu. As we want
to remain portable to other runtimes, even on Windows, we do not use %Iu, but instead expand it logically
to either %lu or %llu depending on if it's _WIN32 or _WIN64 headers.
On POSIX, we assume C99 support is available and always use %zu, as pkgconf has never supported anything
earlier than C99 officially.
Closes#125.
Fixes this build error with mingw:
...
| compilation terminated.
| In file included from ../pkgconf-1.3.7/libpkgconf/libpkgconf.h:19:0,
| from ../pkgconf-1.3.7/libpkgconf/audit.c:16:
| ../pkgconf-1.3.7/libpkgconf/stdinc.h:36:12: fatal error: BaseTsd.h: No
such file or directory
| # include <BaseTsd.h>
Signed-off-by: Maxin B. John <maxin.john@intel.com>