4.4.0-96.119) is not available, but a newer one is (4.4.0-142.168). We redirected you there.
/usr/bin/dtxgen is in texlive-extra-utils 2016.20170123-5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/../share/texlive/texmf-dist/scripts/dtxgen/dtxgen