This gives more information about the failure.
Additionally 'ENOSYS' returned for a non-Linux platforms instead of
'errno', which is not initilaized in this case.

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190311135850.6537-5-i.maximets@samsung.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>