aio_*: avoid busy loop when waiting for aiocb completion

Add sleep to avoid the busy loop when waiting for the aiocb
completion.

Acked-by: Cyril Hrubis <chrubis@suse.cz>
Acked-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
25 files changed