patch 8.1.0777: Win32: using pipes for channel does not work well

Problem:    Win32: using pipes for channel does not work well.
Solution:   Use a larger buffer and handle overlaps. (Yasuhiro Matsumoto,
            closes #3782)
diff --git a/src/version.c b/src/version.c
index da4b2b6..a83bad6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -792,6 +792,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    777,
+/**/
     776,
 /**/
     775,