patch 8.0.0964: channel write buffer does not work with poll()

Problem:    Channel write buffer does not work with poll().
Solution:   Use the same mechanism as with select().
diff --git a/src/version.c b/src/version.c
index e6626cb..291ccdf 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    964,
+/**/
     963,
 /**/
     962,