py: Add new Xtensa-Windowed arch for native emitter.

Enabled via the configuration MICROPY_EMIT_XTENSAWIN.
diff --git a/py/persistentcode.h b/py/persistentcode.h
index 67c5f34..aba44ea 100644
--- a/py/persistentcode.h
+++ b/py/persistentcode.h
@@ -44,6 +44,7 @@
     MP_NATIVE_ARCH_ARMV7EMSP,
     MP_NATIVE_ARCH_ARMV7EMDP,
     MP_NATIVE_ARCH_XTENSA,
+    MP_NATIVE_ARCH_XTENSAWIN,
 };
 
 mp_raw_code_t *mp_raw_code_load(mp_reader_t *reader);