Disable vcut by default.
This probably needs some changes if people want to be able to enable it without
editing configure.in, but vcut is sufficiently broken that people probably
shouldn't be able to do that too easily.
git-svn-id: http://svn.xiph.org/trunk/vorbis-tools@5855 0101bb08-14d6-0310-b084-bc0e0c8e3800