patch 8.2.0500: using the same loop in many places

Problem:    Using the same loop in many places.
Solution:   Define more FOR_ALL macros. (Yegappan Lakshmanan, closes #5339)

src/ex_cmds2.c

@@ -303,7 +303,7 @@ check_changed_any(
     // buffers in other tabs
     FOR_ALL_TABPAGES(tp)
 	if (tp != curtab)
-	    for (wp = tp->tp_firstwin; wp != NULL; wp = wp->w_next)
+	    FOR_ALL_WINDOWS_IN_TAB(tp, wp)
 		add_bufnum(bufnrs, &bufnum, wp->w_buffer->b_fnum);
 
     // any other buffer
@@ -477,7 +477,7 @@ ex_listdo(exarg_T *eap)
 	// great speed improvement.
 	save_ei = au_event_disable(",Syntax");
 
-	for (buf = firstbuf; buf != NULL; buf = buf->b_next)
+	FOR_ALL_BUFFERS(buf)
 	    buf->b_flags &= ~BF_SYN_SET;
 	buf = curbuf;
     }