Merge branch 'Fix-i686-build-with-GCC-v14'

This fixes a long-time compile warning turned error by GCC v14.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

git-compat-util.h

@@ -166,7 +166,7 @@ struct strbuf;
 /* Approximation of the length of the decimal representation of this type. */
 #define decimal_length(x)	((int)(sizeof(x) * 2.56 + 0.5) + 1)
 
-#ifdef __MINGW64__
+#if defined(__MINGW32__) || defined(__MINGW64__)
 #define _POSIX_C_SOURCE 1
 #elif defined(__sun__)
  /*