Log Message:
Update ATF to 0.20.

This change upgrades devel/atf to 0.20 and removes devel/atf-libs.  The
upstream atf distfile has dropped the code for the deprecated tools so
it makes little sense to keep the two packages any longer.

As a result of this, the devel/atf package is now much simplified as
there is no need for a Makefile.common any longer and matches exactly
what upstream ships.

Changes in version 0.20
***********************

Experimental version released on February 7th, 2014.

This is the first release without the code for the deprecated tools.  If
you require such code, please fetch a copy of the 0.19 release and extract
the 'tools' directory for your own consumption.

* Removed the deprecated tools.  This includes atf-config, atf-report,
  atf-run and atf-version.

Changes in version 0.19
***********************

Experimental version released on February 7th, 2014.

This is the last release to bundle the code for the deprecated tools.
The next release will drop their code and will stop worrying about
backwards compatibility between the ATF libraries and what the old tools
may or may not support.

If you still require the old tools for some reason, grab a copy of the
'tools' directory now.  The code in this directory is standalone and
does not depend on any internal details of atf-c++ any longer.

* Various fixes and improvements to support running as part of the FreeBSD
  test suite.

* Project hosting moved from Google Code (as a subproject of Kyua) to
  GitHub (as a first-class project).  The main reason for the change is
  the suppression of binary downloads in Google Code on Jan 15th, 2014.
  See https://github.com/jmmv/atf/

* Removed builtin help from atf-sh(1) and atf-check(1) for simplicity
  reasons.  In other words, their -h option is gone.

* Moved the code of the deprecated tools into a 'tools' directory and
  completely decoupled their code from the internals of atf-c++.  The
  reason for this is to painlessly allow a third-party to maintain a
  copy of these tools after we delete them because upcoming changes to
  atf-c++ would break the stale tools.