Property definitions

pthreads $ NativePthreadCond :: new
	new `{
		pthread_cond_t cond;
		int r = pthread_cond_init(&cond, NULL);
		if (r == 0) {
			pthread_cond_t *pcond = malloc(sizeof(pthread_cond_t));
			memmove(pcond, &cond, sizeof(pthread_cond_t));
			return pcond;
		}
		return NULL;
	`}
lib/pthreads/pthreads.nit:274,2--283,3