patch 9.1.0673: Vim9: too recursive func calls when calling super-class method

Problem:  Vim9: too recursive func calls when calling super-class method
          with non-overriden super-call methods. (Aliaksei Budavei)
Solution: use interface method, when super is to be used (Ernie Rael)

When compiling "super.Func()" force class context to class that defines
function that is doing "super.Func()".
ISN_METHODCALL arg "cmf_is_super" for specific ufunc.

fixes: #15448
fixes: #15463 (2) super.method may not execute in context of defining
                  class
closes: #15477

Signed-off-by: Ernie Rael <errael@raelity.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/vim9.h b/src/vim9.h
index 54938fe..c502ac4 100644
--- a/src/vim9.h
+++ b/src/vim9.h
@@ -238,8 +238,9 @@
 // arguments to ISN_METHODCALL
 typedef struct {
     class_T *cmf_itf;	    // interface used
-    int	    cmf_idx;	    // index in "def_functions" for ISN_DCALL
+    int	    cmf_idx;	    // index in "def_functions" for ISN_METHODCALL
     int	    cmf_argcount;   // number of arguments on top of stack
+    int	    cmf_is_super;   // doing "super.Func", use cmf_itf, not cmf_idx
 } cmfunc_T;
 
 // arguments to ISN_PCALL