[Dovecot] Kerberos check logic incorrect

In configure.in, there is a check that does krb5-config --version | grep -v 1\.2, making sure there is no "1.2" in the version of Kerberos in use. This is to prevent compiling against MIT Kerberos version 1.2, which is too old for Dovecot.

Unfortunately for this idea, Heimdal 1.2.1 is out. And Dovecot builds fine against it.

Whoever committed this check also appears to have removed the comment warning that it was broken, to add insult to injury.

Please fix your checks to be for FEATURES, not version numbers. You never know when something else that correctly implements the features you want will come along.

Bryan Jacobs