libkrb5.so, what was being used as reference to security/krb5 dependency, is
present in base, then port was detecting it and not registering dependency
correctly. After installation, libsss_ldap.so was linked against libk5crypto.so
but it was not present in the system. Replace explicit dependency by USES
gssapi:mit and bump PORTREVISION

Approved by: portmgr (blanket)