patch 8.1.0877: new buffer used every time the quickfix window is opened

Problem:    New buffer used every time the quickfix window is opened.
Solution:   Reuse the buffer. (Yegappan Lakshmanan, closes #3902)
diff --git a/src/version.c b/src/version.c
index dbf0cab..3ad7869 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    877,
+/**/
     876,
 /**/
     875,