Use AC_CANONICAL_HOST for detecting cross-compilation environment
AC_CANONICAL_HOST should be used instead of AC_CANONICAL_TARGET in configure.ac.
This is an issue in vorbis, theora and vorbis-tools. The last two need a patch similar to https://trac.xiph.org/changeset/13007 and for vorbis/configure.ac AC_CANONICAL_TARGET needs to be replaced by AC_CANONICAL_HOST