librbd: Allow get_lock_info to fail

If the lock class isn't present, EOPNOTSUPP is returned for lock calls
on newer OSDs, but sadly EIO on older; we need to treat both as
acceptable failures for RBD images.  rados lock list will still fail.

Fixes #3744.

Signed-off-by: Dan Mick <dan.mick@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
rgw: fix handler leak in handle_request

Fixes: #3682
Signed-off-by: caleb miles <caleb.miles@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
rgw: Fix crash when FastCGI frontend doesn't set SCRIPT_URI

Fixes: #3735
Signed-off-by: caleb miles <caleb.miles@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>