stackctrl: Encode "recursion depth exceeded" message as qstr.

So corresponding exception can be thrown even under tight memory conditions.

py/qstrdefs.h

@@ -385,6 +385,7 @@ Q(qstr_info)
 #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF && (MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE == 0)
 Q(alloc_emergency_exception_buf)
 #endif
+Q(maximum recursion depth exceeded)
 
 Q(<module>)
 Q(<lambda>)

py/stackctrl.c

@@ -48,7 +48,8 @@ void mp_stack_set_limit(mp_uint_t limit) {
 
 void mp_stack_check(void) {
     if (mp_stack_usage() >= MP_STATE_VM(stack_limit)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_RuntimeError, "maximum recursion depth exceeded"));
+        nlr_raise(mp_obj_new_exception_arg1(&mp_type_RuntimeError,
+            MP_OBJ_NEW_QSTR(MP_QSTR_maximum_space_recursion_space_depth_space_exceeded)));
     }
 }