pbsys/host: Quiet -Werror=uninitialized.

Assign values to output parameters when PBSYS_CONFIG_HOST is disabled
to avoid compiler warnings.

Author: dlech

lib/pbio/include/pbsys/host.h

@@ -49,8 +49,8 @@ pbio_error_t pbsys_host_send_event(pbio_os_state_t *state, pbio_pybricks_event_t
 #define pbsys_host_stdin_set_callback(callback) { (void)(callback); }
 #define pbsys_host_stdin_flush()
 #define pbsys_host_stdin_get_available() 0
-#define pbsys_host_stdin_read(data, size) PBIO_ERROR_NOT_SUPPORTED
-#define pbsys_host_stdout_write(data, size) { (void)(data); (void)(size); PBIO_ERROR_NOT_SUPPORTED; }
+#define pbsys_host_stdin_read(data, size) ({ *(data) = 0; *(size) = 0; PBIO_ERROR_NOT_SUPPORTED; })
+#define pbsys_host_stdout_write(data, size) ({ *(size) = 0; PBIO_ERROR_NOT_SUPPORTED; })
 #define pbsys_host_tx_is_idle() false
 
 static inline pbio_error_t pbsys_host_send_event(pbio_os_state_t *state, pbio_pybricks_event_t event_type, const uint8_t *data, size_t size) {