Continue after KRB5_CC_END in KCM cache iteration

Continue after KRB5_CC_END in KCM cache iteration

The KCM server returns KRB5_CC_END in response to a GET_CACHE_BY_UUID
request to indicate that the specified ccache uuid no longer exists.
In krb5_ptcursor_next(), ignore this error and continue the iteration,
as the Heimdal KCM client code does.

In addition to addressing the case where a third party deletes a cache
between the GET_CACHE_UUID_LIST request and when we reach that uuid in
the iteration, this change also fixes a bug in kdestroy -A where the
caller deletes the primary cache and we later request it by uuid when
iterating over the list.

[ghudson@mit.edu: rewrote commit message; edited comment]

ticket: 8658 (new)
tags: pullup
target_version: 1.16-next
target_version: 1.15-next