patch 8.1.0253: saving and restoring window title does not always work

Problem:    Saving and restoring window title does not always work.
Solution:   Use the stack push and pop commands. (Kouichi Iwamoto,
            closes #3059)
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 0539a51..294fbdb 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -7750,7 +7750,7 @@
 	stoptermcap();
 	out_flush();		/* needed for SUN to restore xterm buffer */
 #ifdef FEAT_TITLE
-	mch_restore_title(3);	/* restore window titles */
+	mch_restore_title(SAVE_RESTORE_BOTH);	/* restore window titles */
 #endif
 	ui_suspend();		/* call machine specific function */
 #ifdef FEAT_TITLE