patch 8.0.1305: writefile() never calls fsync()

Problem:    Writefile() never calls fsync().
Solution:   Follow the 'fsync' option with override to enable or disable.
diff --git a/src/fileio.c b/src/fileio.c
index fbc164a..e76e3d1 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4771,7 +4771,7 @@
 	 */
 	if (p_fs && fsync(fd) != 0 && !device)
 	{
-	    errmsg = (char_u *)_("E667: Fsync failed");
+	    errmsg = (char_u *)_(e_fsync);
 	    end = 0;
 	}
 #endif