patch 8.2.3547: opening the quickfix window triggers BufWinEnter twice

Problem:    Opening the quickfix window triggers BufWinEnter twice. (Yorick
            Peterse)
Solution:   Only trigger BufWinEnter with "quickfix". (closes #9022)
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index ff91517..079dcf1 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -2473,6 +2473,7 @@
  *	ECMD_FORCEIT: ! used for Ex command
  *	 ECMD_ADDBUF: don't edit, just add to buffer list
  *	 ECMD_ALTBUF: like ECMD_ADDBUF and also set the alternate file
+ *   ECMD_NOWINENTER: Do not trigger BufWinEnter
  *   oldwin: Should be "curwin" when editing a new buffer in the current
  *	     window, NULL when splitting the window first.  When not NULL info
  *	     of the previous buffer for "oldwin" is stored.
@@ -3030,6 +3031,8 @@
 	    /*
 	     * Open the buffer and read the file.
 	     */
+	    if (flags & ECMD_NOWINENTER)
+		readfile_flags |= READ_NOWINENTER;
 #if defined(FEAT_EVAL)
 	    if (should_abort(open_buffer(FALSE, eap, readfile_flags)))
 		retval = FAIL;
@@ -3051,10 +3054,11 @@
 	    // changed by the user.
 	    do_modelines(OPT_WINONLY);
 
-	    apply_autocmds_retval(EVENT_BUFENTER, NULL, NULL, FALSE, curbuf,
-								    &retval);
-	    apply_autocmds_retval(EVENT_BUFWINENTER, NULL, NULL, FALSE, curbuf,
-								    &retval);
+	    apply_autocmds_retval(EVENT_BUFENTER, NULL, NULL, FALSE,
+							      curbuf, &retval);
+	    if ((flags & ECMD_NOWINENTER) == 0)
+		apply_autocmds_retval(EVENT_BUFWINENTER, NULL, NULL, FALSE,
+							      curbuf, &retval);
 	}
 	check_arg_idx(curwin);