patch 8.2.3796: the funcexe_T struct members are not named consistently

Problem:    The funcexe_T struct members are not named consistently.
Solution:   Prefix "fe_" to all the members.
diff --git a/src/structs.h b/src/structs.h
index b6c7fce..5b7739e 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1992,15 +1992,15 @@
 //							called_func_argcount)
 //
 typedef struct {
-    int		(* argv_func)(int, typval_T *, int, int);
-    linenr_T	firstline;	// first line of range
-    linenr_T	lastline;	// last line of range
-    int		*doesrange;	// if not NULL: return: function handled range
-    int		evaluate;	// actually evaluate expressions
-    partial_T	*partial;	// for extra arguments
-    dict_T	*selfdict;	// Dictionary for "self"
-    typval_T	*basetv;	// base for base->method()
-    type_T	*check_type;	// type from funcref or NULL
+    int		(* fe_argv_func)(int, typval_T *, int, int);
+    linenr_T	fe_firstline;	// first line of range
+    linenr_T	fe_lastline;	// last line of range
+    int		*fe_doesrange;	// if not NULL: return: function handled range
+    int		fe_evaluate;	// actually evaluate expressions
+    partial_T	*fe_partial;	// for extra arguments
+    dict_T	*fe_selfdict;	// Dictionary for "self"
+    typval_T	*fe_basetv;	// base for base->method()
+    type_T	*fe_check_type;	// type from funcref or NULL
     int		fe_found_var;	// if the function is not found then give an
 				// error that a variable is not callable.
 } funcexe_T;