py/emitglue: Reorder and resize members of mp_raw_code_t.

The mp_raw_code_t struct has been reordered and some members resized.  The
`n_pos_args` member is renamed to `asm_n_pos_args`, and `type_sig` renamed
to `asm_type_sig` to indicate that these are used only for the inline-asm
emitters.  These two members are also grouped together in the struct.

The justifications for resizing the members are:
- `fun_data_len` can be 32-bits without issue
- `n_children` is already limited to 16-bits by
  `mp_emit_common_t::ct_cur_child`
- `scope_flags` is already limited to 16-bits by `scope_t::scope_flags`
- `prelude_offset` is already limited to 16-bits by the argument to
  `mp_emit_glue_assign_native()`
- it's reasonable to limit the maximim number of inline-asm arguments to 12
  (24 bits for `asm_type_sig` divided by 2)

This change helps to reduce frozen code size (and in some cases RAM usage)
in the following cases:
- 64-bit targets
- builds with MICROPY_PY_SYS_SETTRACE enabled
- builds with MICROPY_EMIT_MACHINE_CODE enabled but MICROPY_EMIT_INLINE_ASM
  disabled

With this change, unix 64-bit builds are -4080 bytes in size.  Bare-metal
ports like rp2 are unchanged (because mp_raw_code_t is still 32 bytes on
those 32-bit targets).

Signed-off-by: Damien George <damien@micropython.org>

py/persistentcode.c

@@ -578,10 +578,12 @@ STATIC void save_raw_code(mp_print_t *print, const mp_raw_code_t *rc) {
     } else if (rc->kind == MP_CODE_NATIVE_VIPER || rc->kind == MP_CODE_NATIVE_ASM) {
         // Save basic scope info for viper and asm
         mp_print_uint(print, rc->scope_flags & MP_SCOPE_FLAG_ALL_SIG);
+        #if MICROPY_EMIT_INLINE_ASM
         if (rc->kind == MP_CODE_NATIVE_ASM) {
-            mp_print_uint(print, rc->n_pos_args);
-            mp_print_uint(print, rc->type_sig);
+            mp_print_uint(print, rc->asm_n_pos_args);
+            mp_print_uint(print, rc->asm_type_sig);
         }
+        #endif
     }
     #endif