objfun: Add local header.

This follows pattern already used for objtuple, etc.: objfun.h's content
is not public - each and every piece of code should not have access to it.
It's not private either - with out architecture and implementation language
(C) it doesn't make sense to keep implementation of each object strictly
private and maintain cumbersome accessors. It's "local" - intended to be
used by a small set of "friend" (in C++ terms) objects.

py/objfun.c

@@ -9,6 +9,7 @@
 #include "qstr.h"
 #include "obj.h"
 #include "objtuple.h"
+#include "objfun.h"
 #include "runtime0.h"
 #include "runtime.h"
 #include "bc.h"
@@ -150,18 +151,6 @@ mp_obj_t mp_make_function_var_between(int n_args_min, int n_args_max, mp_fun_var
 /******************************************************************************/
 /* byte code functions                                                        */
 
-typedef struct _mp_obj_fun_bc_t {
-    mp_obj_base_t base;
-    mp_obj_dict_t *globals; // the context within which this function was defined
-    machine_uint_t n_args : 15;         // number of arguments this function takes
-    machine_uint_t n_def_args : 15;     // number of default arguments
-    machine_uint_t takes_var_args : 1;  // set if this function takes variable args
-    machine_uint_t takes_kw_args : 1;   // set if this function takes keyword args
-    const byte *bytecode;   // bytecode for the function
-    qstr *args;             // argument names (needed to resolve positional args passed as keywords)
-    mp_obj_t extra_args[];  // values of default args (if any), plus a slot at the end for var args and/or kw args (if it takes them)
-} mp_obj_fun_bc_t;
-
 #if DEBUG_PRINT
 STATIC void dump_args(const mp_obj_t *a, int sz) {
     DEBUG_printf("%p: ", a);

py/objfun.h

@@ -0,0 +1,12 @@
+typedef struct _mp_obj_fun_bc_t {
+    mp_obj_base_t base;
+    mp_obj_dict_t *globals; // the context within which this function was defined
+    machine_uint_t n_args : 15;         // number of arguments this function takes
+    machine_uint_t n_def_args : 15;     // number of default arguments
+    machine_uint_t takes_var_args : 1;  // set if this function takes variable args
+    machine_uint_t takes_kw_args : 1;   // set if this function takes keyword args
+    const byte *bytecode;   // bytecode for the function
+    qstr *args;             // argument names (needed to resolve positional args passed as keywords)
+    // values of default args (if any), plus a slot at the end for var args and/or kw args (if it takes them)
+    mp_obj_t extra_args[];
+} mp_obj_fun_bc_t;