* sysdeps/pthread/aio_misc.h: Mark __aio_requests_mutex,
__aio_enqueue_request, __aio_find_req, __aio_find_req_fd,
__aio_free_request, __aio_notify, and __aio_sigqueue as hidden.
* sysdeps/pthread/aio_suspend.c (aio_suspend): Set errno to the result
of pthread_cond_wait if there was an error. Use pthread_cleanup_*
instead of __lbic_cleanup_region_*.
* sysdeps/unix/clock_nanosleep.c (clock_nanosleep): nanosleep
takes care of enabling cancellation.
* sysdeps/pthread/aio_suspend.c (aio_suspend): Make aio_suspend
cancelable. It's not correct to disable cancellation. Instead of
a cleanup handler.