Original commit message from CVS:
* configure.ac:
Disable libvisual

* examples/Makefile.am:
* gst-libs/gst/audio/Makefile.am:
* gst-libs/gst/riff/Makefile.am:
* gst-libs/gst/tag/Makefile.am:
* gst-libs/gst/video/Makefile.am:
Fixups for missing variables.