void _xcb_wait_io(xcb_connection_t *c, pthread_cond_t *cond);
int _xcb_conn_wait(xcb_connection_t *c, pthread_cond_t *cond, struct iovec **vector, int *count);
void _xcb_wait_io(xcb_connection_t *c, pthread_cond_t *cond);
int _xcb_conn_wait(xcb_connection_t *c, pthread_cond_t *cond, struct iovec **vector, int *count);