Free temporary string in FcDirCacheUnlink (Bug #11758)

In FcDirCacheUnlink(), the line

  cache_hashed = FcStrPlus (cache_dir, cache_base);

allocates memory in cache_hashed that is never free()'d before the function
exits.

Reported by Ben Combee.

src/fccache.c

@@ -104,6 +104,7 @@ FcDirCacheUnlink (const FcChar8 *dir, FcConfig *config)
         if (!cache_hashed)
 	    break;
 	(void) unlink ((char *) cache_hashed);
+	FcStrFree (cache_hashed);
     }
     FcStrListDone (list);
     /* return FcFalse if something went wrong */