patch 8.0.0208: internally used commands end up in history

Problem:    Internally used commands for CTRL-Z and mouse click end up in
            history. (Matthew Malcomson)
Solution:   Use do_cmdline_cmd() instead of stuffing them in the readahead
            buffer. (James McCoy, closes #1395)
diff --git a/src/normal.c b/src/normal.c
index 3456b73..8724553 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -2982,9 +2982,9 @@
 	if (State & INSERT)
 	    stuffcharReadbuff(Ctrl_O);
 	if (curwin->w_llist_ref == NULL)	/* quickfix window */
-	    stuffReadbuff((char_u *)":.cc\n");
+	    do_cmdline_cmd((char_u *)".cc");
 	else					/* location list window */
-	    stuffReadbuff((char_u *)":.ll\n");
+	    do_cmdline_cmd((char_u *)".ll");
 	got_click = FALSE;		/* ignore drag&release now */
     }
 #endif