When "ar" is not found fall back to ${CHOST}-ar.

https://bugs.gentoo.org/728638
--- a/gcc/gcc-ar.c
+++ b/gcc/gcc-ar.c
@@ -194,9 +194,7 @@ main (int ac, char **av)
   if (!exe_name)
     {
       const char *real_exe_name = PERSONALITY;
-#ifdef CROSS_DIRECTORY_STRUCTURE
       real_exe_name = concat (target_machine, "-", PERSONALITY, NULL);
-#endif
       exe_name = find_a_file (&path, real_exe_name, X_OK);
       if (!exe_name)
 	{