Suppress unused-variables warning when OPEN_SYNC_FLAG isn't defined.

Per buildfarm.

Author: tglsfdc

contrib/pg_test_fsync/pg_test_fsync.c

@@ -391,16 +391,15 @@ test_open_syncs(void)
 	test_open_sync("16  1k open_sync writes", 1);
 }
 
-
+/*
+ * Test open_sync with different size files
+ */
 static void
 test_open_sync(const char *msg, int writes_size)
 {
+#ifdef OPEN_SYNC_FLAG
 	int		tmpfile, ops, writes;
 
-/*
- * Test open_sync with different size files
- */
-#ifdef OPEN_SYNC_FLAG
 	if ((tmpfile = open(filename, O_RDWR | OPEN_SYNC_FLAG | PG_O_DIRECT, 0)) == -1)
 		printf(NA_FORMAT, "o_direct", "n/a**\n");
 	else