patch 9.0.1041: cannot define a method in a class

Problem:    Cannot define a method in a class.
Solution:   Implement defining an object method.  Make calling an object
            method work.
diff --git a/src/vim.h b/src/vim.h
index e241da0..f197fda 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -2676,7 +2676,8 @@
 #define TFN_NO_DECL	0x20	// only used for GLV_NO_DECL
 #define TFN_COMPILING	0x40	// only used for GLV_COMPILING
 #define TFN_NEW_FUNC	0x80	// defining a new function
-#define TFN_ASSIGN_WITH_OP	0x100	// only for GLV_ASSIGN_WITH_OP
+#define TFN_ASSIGN_WITH_OP 0x100  // only for GLV_ASSIGN_WITH_OP
+#define TFN_IN_CLASS	0x200	// function in a class
 
 // Values for get_lval() flags argument:
 #define GLV_QUIET	TFN_QUIET	// no error messages