mit-kerberos: Update to 1.18.2

Upstream README excerpt:

Major changes in 1.18.2 (2020-05-21)

    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.

Major changes in 1.18.1 (2020-04-13)

    Fix a crash when qualifying short hostnames when the system has no primary DNS domain.
    Fix a regression when an application imports "service@" as a GSS host-based name for its acceptor credential handle.
    Fix KDC enforcement of auth indicators when they are modified by the KDB module.
    Fix removal of require_auth string attributes when the LDAP KDB module is used.
    Fix a compile error when building with musl libc on Linux.
    Fix a compile error when building with gcc 4.x.
    Change the KDC constrained delegation precedence order for consistency with Windows KDCs.

(gdt)