patch 8.1.0800: may use a lot of memory when a function refers itself

Problem:    May use a lot of memory when a function creates a cyclic
            reference.
Solution:   After saving a funccal many times, invoke the garbage collector.
            (closes #3835)
diff --git a/src/version.c b/src/version.c
index d5ea086..b8b0630 100644
--- a/src/version.c
+++ b/src/version.c
@@ -792,6 +792,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    800,
+/**/
     799,
 /**/
     798,