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/globals.h b/src/globals.h
index 2d64686..6faee3b 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1592,6 +1592,7 @@
 EXTERN char e_zerocount[]	INIT(= N_("E939: Positive count required"));
 #ifdef FEAT_EVAL
 EXTERN char e_usingsid[]	INIT(= N_("E81: Using <SID> not in a script context"));
+EXTERN char e_missingparen[]	INIT(= N_("E107: Missing parentheses: %s"));
 #endif
 #ifdef FEAT_CLIENTSERVER
 EXTERN char e_invexprmsg[]	INIT(= N_("E449: Invalid expression received"));