qemu-nbd: Clean up "Failed to load snapshot" error message

bdrv_snapshot_load_tmp() sets an error and returns -errno on failure.
We report both even though the error message is self-contained.  Drop
the redundant strerror().

While there: setting errno right before exit() is pointless, so drop
that, too.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1450452927-8346-8-git-send-email-armbru@redhat.com>

0 files changed, 0 insertions, 0 deletions