patch 8.1.1803: all builtin functions are global

Problem:    All builtin functions are global.
Solution:   Add the method call operator ->.  Implemented for a limited number
            of functions.
diff --git a/src/version.c b/src/version.c
index 6268b8e..5e027dd 100644
--- a/src/version.c
+++ b/src/version.c
@@ -774,6 +774,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1803,
+/**/
     1802,
 /**/
     1801,