aio: report error from io_destroy() when threads race in io_destroy()
aio: report error from io_destroy() when threads race in io_destroy()

As reported by Anatol Pomozov, io_destroy() fails to report an error when
it loses the race to destroy a given ioctx.  Since there is a difference in
behaviour between the thread that wins the race (which blocks on outstanding
io requests) versus lthe thread that loses (which returns immediately), wire
up a return code from kill_ioctx() to the io_destroy() syscall.

Signed-off-by: Benjamin LaHaise <b05c66fa21e46731bb89a779db663748f3df8f6a@kvack.org>
Cc: Anatol Pomozov <5d78902c885bda21bab1f3f4d20718dff0167f20@gmail.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs