Update 1.18.1 --> 1.18.2

This is a bug fix release.

• Fix a SPNEGO regression where an acceptor using the default credential would improperly filter mechanisms, causing a negotiation failure.

• Fix a bug where the KDC would fail to issue tickets if the local krbtgt principal's first key has a single-DES enctype.

• Add stub functions to allow old versions of OpenSSL libcrypto to link against libkrb5.

• Fix a NegoEx bug where the client name and delegated credential might not be reported.