fix some similar but unrelated bugs where the PHYSFS_close() return value is
misinterpreted. Can still not select forces from the multiplayer dialog,
but I also have no idea how this is supposed to work.
git-svn-id: svn+ssh://svn.gna.org/svn/warzone/trunk@542 4a71c877-e1ca-e34f-864e-861f7616d084