Fix for r3669, because our build machine (and untold others in the wider
world) have an old copy of svnversion, which demands a workspace-directory
argument.

TBR: scottb



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@3670 8db76d5a-ed1c-0410-87a9-c151d255dfc7