Make the building of the ActionScript code optional, depending on whether flexsdk.dir is provided or can be inferred.
Make the building of the ActionScript code optional, depending on whether
flexsdk.dir is provided or can be inferred.

git-svn-id: b675b909355d5cf946977f44a8ec5a6ceb3782e4@1171 ed5b42cb-e716-0410-a449-f6a68f950b19

threerings/nenya,threerings/nenya