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'.
This includes C-API bindings in intern/opensubdiv and CMAke module
which finds the OpenSubdiv library. This filea are not in use so
far, making it a separate commit to make actual integration commit
more clear.
