[EFL] Add a WebKit2 Performance bot.
https://bugs.webkit.org/show_bug.cgi?id=109188

Reviewed by Csaba Osztrogonác.

* BuildSlaveSupport/build.webkit.org-config/config.json: Add the
efl-linux-perf-1 slave (a 64-bit Release WK2 Perf bot), and make
the "EFL Linux 64-bit Release" bot trigger it.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@142121 268f45cc-cd09-0410-ab3c-d52691b4dbfc