patch 8.2.0684: Vim9: memory leak when using lambda

Problem:    Vim9: memory leak when using lambda.
Solution:   Move the funccal context to the partial. Free the function when
            exiting.

src/vim9.h

@@ -259,21 +259,6 @@ struct isn_S {
     } isn_arg;
 };
 
-/*
- * Structure to hold the context of a compiled function, used by closures
- * defined in that function.
- */
-typedef struct funcstack_S
-{
-    garray_T	fs_ga;		// contains the stack, with:
-				// - arguments
-				// - frame
-				// - local variables
-
-    int		fs_refcount;	// nr of closures referencing this funcstack
-    int		fs_copyID;	// for garray_T collection
-} funcstack_T;
-
 /*
  * Info about a function defined with :def.  Used in "def_functions".
  */
@@ -286,11 +271,6 @@ struct dfunc_S {
     isn_T	*df_instr;	    // function body to be executed
     int		df_instr_count;
 
-    garray_T	*df_ectx_stack;	    // where compiled closure finds local vars
-    int		df_ectx_frame;	    // index of function frame in uf_ectx_stack
-    funcstack_T	*df_funcstack;	    // copy of stack for closure, used after
-				    // closure context function returns
-
     int		df_varcount;	    // number of local variables
     int		df_closure_count;   // number of closures created
 };