patch 9.1.0639: channel timeout may wrap around

Problem:  channel timeout may wrap around
Solution: Correct timeout calculation when GetTickCount() wraps around
          (Ken Takata)

closes: #15390

Signed-off-by: Ken Takata <kentkt@csc.jp>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/channel.c b/src/channel.c
index b99b3a9..69bbff2 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -2277,7 +2277,7 @@
 	{
 	    int timeout;
 #ifdef MSWIN
-	    timeout = GetTickCount() > chanpart->ch_deadline;
+	    timeout = (int)(GetTickCount() - chanpart->ch_deadline) > 0;
 #else
 	    {
 		struct timeval now_tv;