Don't do it only in the successful case since the handle is
not useful afterwards and later calls might otherwise reuse the handle.

Also don't use the handle in the error path after pam_end.
Signed-off-by: Guido Günther <guido.gunther@puri.sm>

Detects missing includes and missing static defitions

Be pessimistic and assume failure when the pam handle did not get
cleanued up earlier.

It's guaranteed to exist.

For now compare an N digit PIN