config.h: fix compilation on mingw32-w64

          (merge https://trac.osgeo.org/grass/changeset/67055 from trunk)


git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@67084 15284696-431f-4ddb-bdfa-cd5b030d7da7

include/config.h.in

@@ -276,7 +276,7 @@
 
 #endif
 
-#if defined(__MINGW32__)
+#if defined(__MINGW32__) && (!defined(_FILE_OFFSET_BITS) || (_FILE_OFFSET_BITS != 64))
 
 /* add/remove as needed */
 /* redefine off_t */