synergy: project has moved from synergy.googlecode.com

The synergy project on synergy.googlecode.com is defunct. The
sources cannot be downloaded from there anymore. The new project
home is synergy-project.org, but sources can only be downloaded
from ther with a login. The source code repo is on github.com/synergy.

New recipe to check out the code from GitHub. The code contains
zip archives for gmock and gtest, which need to be extracted before
do_configure. The license file has changed from COPYING to LICENSE. The
authors apparently added their copyright information before the GPLv2
license text. Hence, the md5sum is different.

Signed-off-by: Rudolf J Streif <rudolf.streif@gmail.com>