This reverts commit
79361eede240e9591891290c22cd072ccddb78a3.
Just commenting out a test without an explanation does not
look right to me. This needs at the minimum a link to a
bug report or an explanation for why the behaviour is platform
dependent. If the test was just wrong, it needs to be removed,
not commented out. If there is a bug in the win32 implementation,
it needs to be fixed.
/* Test also using the slash as file name separator */
#define U "/"
-/* check_string (g_build_filename (NULL), "");*/
+ check_string (g_build_filename (NULL), "");
check_string (g_build_filename (U, NULL), U);
check_string (g_build_filename (U"x", NULL), U"x");
check_string (g_build_filename ("x"U, NULL), "x"U);