Original commit message from CVS: add FreeBSD patches from Andrew Turner and add missing ivorbis m4 to cvs, also disable ivorbis plugin as the test mistakes ordinary vorbis for tremor
All aclocal .m4 files we need are put here and cat'd to acinclude.m4 in the source root. Official ones (taken from the relevant devel packages) are named as-is, unofficial ones (or changed ones) get a gst-prefix.