Unlink correct files in salvager

Unlink correct files in salvager

Fallout from 0ac956b3384842b3c60e72bde78a4baf58a5877f; a couple of
unlink() calls were not updated to use the absolute path. Update them,
and log errors from unlink(), since otherwise it is difficult to tell
that anything is going wrong.

Reviewed-on: http://gerrit.openafs.org/479
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 29ee678f3ab051a27cae46b02a0d42e0958a6bc8)
Change-Id: Ic7bc1f3470e705f03fee044f438804cdd211db6b
Reviewed-on: http://gerrit.openafs.org/962