rxgen, kauth: Set but not used variables

rxgen, kauth: Set but not used variables

Remove a few variables that are not actually used, and the
associated code.

foundcurrentkey is only used in the AUTH_DBM_LOG case, so
scope the declaration and assignment accordingly.

Spotted by gcc 4.6

Change-Id: I281ca37488e69bfe46a8e63bdc5990f5f3cff940
Reviewed-on: http://gerrit.openafs.org/2734
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>