py/compile: Add mp_compile_to_raw_code() to return raw code object.

This can then be passed to mp_raw_code_save_file to save a .mpy file.

py/compile.c

@@ -3090,7 +3090,10 @@ STATIC void scope_compute_things(scope_t *scope) {
     }
 }
 
-mp_obj_t mp_compile(mp_parse_tree_t *parse_tree, qstr source_file, uint emit_opt, bool is_repl) {
+#if !MICROPY_PERSISTENT_CODE_SAVE
+STATIC
+#endif
+mp_raw_code_t *mp_compile_to_raw_code(mp_parse_tree_t *parse_tree, qstr source_file, uint emit_opt, bool is_repl) {
     // put compiler state on the stack, it's relatively small
     compiler_t comp_state = {0};
     compiler_t *comp = &comp_state;
@@ -3263,7 +3266,12 @@ mp_obj_t mp_compile(mp_parse_tree_t *parse_tree, qstr source_file, uint emit_opt
     if (comp->compile_error != MP_OBJ_NULL) {
         nlr_raise(comp->compile_error);
     } else {
-        // return function that executes the outer module
-        return mp_make_function_from_raw_code(outer_raw_code, MP_OBJ_NULL, MP_OBJ_NULL);
+        return outer_raw_code;
     }
 }
+
+mp_obj_t mp_compile(mp_parse_tree_t *parse_tree, qstr source_file, uint emit_opt, bool is_repl) {
+    mp_raw_code_t *rc = mp_compile_to_raw_code(parse_tree, source_file, emit_opt, is_repl);
+    // return function that executes the outer module
+    return mp_make_function_from_raw_code(rc, MP_OBJ_NULL, MP_OBJ_NULL);
+}

py/compile.h

@@ -43,6 +43,11 @@ enum {
 // the compiler will clear the parse tree before it returns
 mp_obj_t mp_compile(mp_parse_tree_t *parse_tree, qstr source_file, uint emit_opt, bool is_repl);
 
+#if MICROPY_PERSISTENT_CODE_SAVE
+// this has the same semantics as mp_compile
+mp_raw_code_t *mp_compile_to_raw_code(mp_parse_tree_t *parse_tree, qstr source_file, uint emit_opt, bool is_repl);
+#endif
+
 // this is implemented in runtime.c
 mp_obj_t mp_parse_compile_execute(mp_lexer_t *lex, mp_parse_input_kind_t parse_input_kind, mp_obj_dict_t *globals, mp_obj_dict_t *locals);