rather than trying to build a single .app with both 10.4 and 10.5 fuse
libraries embedded within it, for the time being, we're just going to
have independant 10.4 and 10.5 builds.
this provides a 10.5 _fusemodule.so, and build changes to copy the
appropriate versions of files for 10.4 or 10.5 from sub dirs of mac/
into the build tree before triggering py2app
