lib/utils/interrupt_char: Use core-provided mp_kbd_exception if enabled.

Ultimately all ports that use lib/utils/interrupt_char would enable
MICROPY_KBD_EXCEPTION, so this is an interim solution.

lib/utils/interrupt_char.c

@@ -31,11 +31,19 @@ int mp_interrupt_char;
 
 void mp_hal_set_interrupt_char(int c) {
     if (c != -1) {
+        #if MICROPY_KBD_EXCEPTION
+        mp_obj_exception_clear_traceback(MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_kbd_exception)));
+        #else
         mp_obj_exception_clear_traceback(MP_STATE_PORT(mp_kbd_exception));
+        #endif
     }
     mp_interrupt_char = c;
 }
 
 void mp_keyboard_interrupt(void) {
+    #if MICROPY_KBD_EXCEPTION
+    MP_STATE_VM(mp_pending_exception) = MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_kbd_exception));
+    #else
     MP_STATE_VM(mp_pending_exception) = MP_STATE_PORT(mp_kbd_exception);
+    #endif
 }