Revert "Revert "pam_krb5: forgot to add md5-cache file""

I just can't decide.

This reverts commit 2f4534697a08d43c92f3aa5a61016e6eb0bd3f2a.
Revert "Revert "pam_krb5: Add 2.4.9 from Fedora Project""

I think I do actually want this.

This reverts commit c5f869dcd9bae55e249460423b97543ad85c3a29.
pambase: Don't hard require a certain version of pam_krb5