patch 8.1.1019: Lua: may garbage collect function reference in use

Problem:    Lua: may garbage collect function reference in use.
Solution:   Keep the function name instead of the typeval. Make luaV_setref()
            handle funcref objects. (Ozaki Kiichi, closes #4127)
diff --git a/src/version.c b/src/version.c
index 18daa06..a32770e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -780,6 +780,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1019,
+/**/
     1018,
 /**/
     1017,