make 'import uerrno' work again in unix port

this fixes tests that 'import uerrno'.

py/moduerrno.c

@@ -105,7 +105,11 @@ const mp_obj_module_t mp_module_uerrno = {
     .globals = (mp_obj_dict_t *)&mp_module_uerrno_globals,
 };
 
+#if defined(MICROPY_UNIX_COVERAGE)
+MP_REGISTER_MODULE(MP_QSTR_uerrno, mp_module_uerrno);
+#else
 MP_REGISTER_MODULE(MP_QSTR_errno, mp_module_uerrno);
+#endif
 
 qstr mp_errno_to_str(mp_obj_t errno_val) {
     // Otherwise, return the Exxxx string for that error code