krb5_cc_set_config has been non-functional since r24753 on cache types
which don't support removal of credential entries.  Fix it by only
calling krb5_cc_remove_cred if data is NULL, since krb5_cc_store_cred
will do it anyway in the positive case.

Also fix an old memory leak in an uncommon error case.

https://github.com/krb5/krb5/commit/c0a51fe0c8051e27c6cee4f4f0c705356a715e1e
Commit By: ghudson
Revision: 25384
Changed Files:
U   trunk/src/lib/krb5/ccache/ccfns.c