Stop using memcache, use mod_auth_gssapi filesystem based ccaches.
Remove custom session handling, use mod_auth_gssapi and mod_session to
establish and keep a session cookie.
Add loopback to mod_auth_gssapi to do form absed auth and pass back a
valid session cookie.
And now that we do not remove ccaches files to move them to the
memcache, we can avoid the risk of pollutting the filesystem by keeping
a common ccache file for all instances of the same user.

https://fedorahosted.org/freeipa/ticket/5959

Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>

At the same time, I've renamed tmpfilesd config file to static name
"ipa.conf" instead of using package-specific name. It had no purpose
and just complicated build and packaging.

Variable substitution into configuration has to be done in Makefile
and not in Autoconf as documented in:
Autoconf v2.69 manual chapter 4.8.2 Installation Directory Variables:
  ... Most of these variables have values that rely on prefix or
  exec_prefix. ... Similarly, you should not rely on AC_CONFIG_FILES
  to replace bindir and friends in your shell scripts and other files;
  instead, let make manage their replacement.

https://fedorahosted.org/freeipa/ticket/6418

Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>