patch 8.1.1027: memory usage test sometimes fails

Problem:    Memory usage test sometimes fails.
Solution:   Use 80% of before.last as the lower limit. (Christian Brabandt)
diff --git a/src/version.c b/src/version.c
index 6b578c8..ee8a4d6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -780,6 +780,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1027,
+/**/
     1026,
 /**/
     1025,