py: Don't include mp_optimise_value or opt_level() if compiler disabled.

Without the compiler enabled the mp_optimise_value is unused, and the
micropython.opt_level() function is not useful, so exclude these from the
build to save RAM and code size.

py/modmicropython.c

@@ -35,6 +35,7 @@
 // Various builtins specific to MicroPython runtime,
 // living in micropython module
 
+#if MICROPY_ENABLE_COMPILER
 STATIC mp_obj_t mp_micropython_opt_level(size_t n_args, const mp_obj_t *args) {
     if (n_args == 0) {
         return MP_OBJ_NEW_SMALL_INT(MP_STATE_VM(mp_optimise_value));
@@ -44,6 +45,7 @@ STATIC mp_obj_t mp_micropython_opt_level(size_t n_args, const mp_obj_t *args) {
     }
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_micropython_opt_level_obj, 0, 1, mp_micropython_opt_level);
+#endif
 
 #if MICROPY_PY_MICROPYTHON_MEM_INFO
 
@@ -158,7 +160,9 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(mp_micropython_schedule_obj, mp_micropython_sch
 STATIC const mp_rom_map_elem_t mp_module_micropython_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_micropython) },
     { MP_ROM_QSTR(MP_QSTR_const), MP_ROM_PTR(&mp_identity_obj) },
+    #if MICROPY_ENABLE_COMPILER
     { MP_ROM_QSTR(MP_QSTR_opt_level), MP_ROM_PTR(&mp_micropython_opt_level_obj) },
+    #endif
 #if MICROPY_PY_MICROPYTHON_MEM_INFO
 #if MICROPY_MEM_STATS
     { MP_ROM_QSTR(MP_QSTR_mem_total), MP_ROM_PTR(&mp_micropython_mem_total_obj) },

py/mpstate.h

@@ -199,7 +199,9 @@ typedef struct _mp_state_vm_t {
     mp_thread_mutex_t qstr_mutex;
     #endif
 
+    #if MICROPY_ENABLE_COMPILER
     mp_uint_t mp_optimise_value;
+    #endif
 
     // size of the emergency exception buf, if it's dynamically allocated
     #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF && MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE == 0

py/runtime.c

@@ -83,8 +83,10 @@ void mp_init(void) {
     MICROPY_PORT_INIT_FUNC;
 #endif
 
+    #if MICROPY_ENABLE_COMPILER
     // optimization disabled by default
     MP_STATE_VM(mp_optimise_value) = 0;
+    #endif
 
     // init global module dict
     mp_obj_dict_init(&MP_STATE_VM(mp_loaded_modules_dict), 3);