Drop the assumption that we're using the main AioContext. The following
functions need to be converted:
* qemu_bh_new() -> aio_bh_new()
* qemu_aio_set_fd_handler() -> aio_set_fd_handler()
* qemu_aio_wait() -> aio_poll()
The .bdrv_detach/attach_aio_context() interfaces also need to be
implemented to move the fd handler from the old to the new AioContext.
Cc: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Peter Lieven <pl@kamp.de>
471799d135