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)

src/version.c

@@ -779,6 +779,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1019,
 /**/
     1018,
 /**/