These slaves have been sitting idle since we removed our Leopard builders in r97496.

Fixes <http://webkit.org/b/73829> REGRESSION (r97496): apple-macpro-7 and apple-xserve-1 are
sitting idle

Reviewed by Sam Weinig.

* BuildSlaveSupport/build.webkit.org-config/config.json: Re-added apple-macpro-7 and
apple-xserve-1. The former is now doing "SnowLeopard Intel Debug (WebKit2 Tests)", which
allows apple-xserve-9 to be a build-only slave, and the latter is doing "Lion Intel Debug
(WebKit2 Tests)".

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@102000 268f45cc-cd09-0410-ab3c-d52691b4dbfc