patch 8.2.5128: syntax disabled when using synID() in searchpair() skip expr

Problem:    Syntax highlighting disabled when using synID() in searchpair()
            skip expression and it times out. (Jaehwang Jung)
Solution:   Add the redrawtime_limit_set flag. (closes #10562)
diff --git a/src/globals.h b/src/globals.h
index 63377af..888f6e9 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1228,6 +1228,10 @@
 #ifdef FEAT_DIFF
 EXTERN int	need_diff_redraw INIT(= 0); // need to call diff_redraw()
 #endif
+#ifdef FEAT_RELTIME
+// flag set when 'redrawtime' timeout has been set
+EXTERN int	redrawtime_limit_set INIT(= FALSE);
+#endif
 
 EXTERN int	need_highlight_changed INIT(= TRUE);