Add svn:executable to a bunch of scripts in BuildSlaveSupport.
Also removed the empty mac directory.

* BuildSlaveSupport/built-product-archive: Added property svn:executable.
* BuildSlaveSupport/download-built-product: Added property svn:executable.
* BuildSlaveSupport/mac: Removed.
* BuildSlaveSupport/test-result-archive: Added property svn:executable.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@138889 268f45cc-cd09-0410-ab3c-d52691b4dbfc