patch 8.0.1081: memory leak for the channel write queue

Problem:    Memory leak for the channel write queue.
Solution:   Free the write queue when clearing a channel.

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1081,
 /**/
     1080,
 /**/