Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- Use __NO_TLS preprocessor value to make assumptions about TLS support
on a platform.

- Update FreeBSD Heimdal distribution to version 1.5.1. This also brings
several new kerberos related libraries and applications to FreeBSD:
o kgetcred(1) allows one to manually get a ticket for a particular service.
o kf(1) securily forwards ticket to another host through an authenticated
and encrypted stream.
o kcc(1) is an umbrella program around klist(1), kswitch(1), kgetcred(1)
and other user kerberos operations. klist and kswitch are just symlinks
to kcc(1) now.
o kswitch(1) allows you to easily switch between kerberos credentials if
you're running KCM.
o hxtool(1) is a certificate management tool to use with PKINIT.
o string2key(1) maps a password into key.
o kdigest(8) is a userland tool to access the KDC's digest interface.
o kimpersonate(8) creates a "fake" ticket for a service.

We also now install manpages for some lirbaries that were not installed
before, libheimntlm and libhx509.

- The new HEIMDAL version no longer supports Kerberos 4. All users are
recommended to switch to Kerberos 5.

- Weak ciphers are now disabled by default. To enable DES support (used
by telnet(8)), use "allow_weak_crypto" option in krb5.conf.

- libtelnet, pam_ksu and pam_krb5 are now compiled with error on warnings
disabled due to the function they use (krb5_get_err_text(3)) being
deprecated. I plan to work on this next.

- Heimdal's KDC now require sqlite to operate. We use the bundled version
and install it as libheimsqlite. If some other FreeBSD components will
require it in the future we can rename it to libbsdsqlite and use for these
components as well.

- This is not a latest Heimdal version, the new one was released while I was
working on the update. I will update it to 1.5.2 soon, as it fixes some
important bugs and security issues.

Convert files to UTF-8 and add some copyright markers where missing.

Fix conflicts after heimdal-1.1 import and add build infrastructure. Import
all non-style changes made by heimdal to our own libgssapi.

If the mech_type argument to gss_display_status is null, use a default
mechanism.

Approved by: re (kensmith)

Merge fixes back from heimdal.

Approved by: re (kensmith)

Add a new extensible GSS-API layer which can support GSS-API plugins,
similar the the Solaris implementation. Repackage the krb5 GSS mechanism
as a plugin library for the new implementation. This also includes a
comprehensive set of manpages for the GSS-API functions with text mostly
taken from the RFC.

Reviewed by: Love Hörnquist Åstrand <lha@it.su.se>, ru (build system), des (openssh parts)