Fix package name missmatch in a few module files. IE "ALEMBIC" was
defined in the file but the find_package commands used "Alembic"
Some modules state that they set and use the _LIBRARY variable but the
do in fact not do this. Removed these comments from those files.
Reduce the number of possible locations used to find libraries,
to simplify troubleshooting.
Only keep '*_ROOT_DIR' and the path used by 'install_deps.sh'.