Lookahead fst libraries are not included in path

Recipes for recently added lookahead decoding fail because lookahead libraries are built in `/lib/fst` rather then `/lib`

adding
`export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$KALDI_ROOT/tools/openfst/lib/fst`
to path.sh solves the problem

Start with path.sh and inspect how the OpenFST library directories are added to LD_LIBRARY_PATH. Check a recently added lookahead decoding recipe that currently fails, and consider the issue resolved when those recipes can find the lookahead libraries without manual environment changes.

Written by the indexing model from the issue text.