patch 8.2.0523: loops are repeated

Problem:    Loops are repeated.
Solution:   Use FOR_ALL_ macros. (Yegappan Lakshmanan, closes #5882)
diff --git a/src/quickfix.c b/src/quickfix.c
index 127811a..5c24bab 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -6276,7 +6276,7 @@
 	win_T	    *wp;
 
 	if (firstwin->w_next != NULL)
-	    for (wp = firstwin; wp != NULL; wp = wp->w_next)
+	    FOR_ALL_WINDOWS(wp)
 		if (wp->w_buffer == buf)
 		{
 		    if (win_close(wp, FALSE) == OK)