/usr/lib/ada/adalib/gnatprj/ is in libgnatprj6-dev 6.3.0-18+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ada/adalib/gnatprj/ali-util.ali
/usr/lib/ada/adalib/gnatprj/ali.ali
/usr/lib/ada/adalib/gnatprj/binderr.ali
/usr/lib/ada/adalib/gnatprj/butil.ali
/usr/lib/ada/adalib/gnatprj/err_vars.ali
/usr/lib/ada/adalib/gnatprj/errout.ali
/usr/lib/ada/adalib/gnatprj/erroutc.ali
/usr/lib/ada/adalib/gnatprj/errutil.ali
/usr/lib/ada/adalib/gnatprj/fmap.ali
/usr/lib/ada/adalib/gnatprj/fname-uf.ali
/usr/lib/ada/adalib/gnatprj/impunit.ali
/usr/lib/ada/adalib/gnatprj/lib-util.ali
/usr/lib/ada/adalib/gnatprj/makeutl.ali
/usr/lib/ada/adalib/gnatprj/mlib-fil.ali
/usr/lib/ada/adalib/gnatprj/mlib-tgt-specific.ali
/usr/lib/ada/adalib/gnatprj/mlib-tgt.ali
/usr/lib/ada/adalib/gnatprj/mlib-utl.ali
/usr/lib/ada/adalib/gnatprj/mlib.ali
/usr/lib/ada/adalib/gnatprj/osint-c.ali
/usr/lib/ada/adalib/gnatprj/osint.ali
/usr/lib/ada/adalib/gnatprj/prj-attr-pm.ali
/usr/lib/ada/adalib/gnatprj/prj-attr.ali
/usr/lib/ada/adalib/gnatprj/prj-com.ali
/usr/lib/ada/adalib/gnatprj/prj-conf.ali
/usr/lib/ada/adalib/gnatprj/prj-dect.ali
/usr/lib/ada/adalib/gnatprj/prj-env.ali
/usr/lib/ada/adalib/gnatprj/prj-err.ali
/usr/lib/ada/adalib/gnatprj/prj-ext.ali
/usr/lib/ada/adalib/gnatprj/prj-makr.ali
/usr/lib/ada/adalib/gnatprj/prj-nmsc.ali
/usr/lib/ada/adalib/gnatprj/prj-pars.ali
/usr/lib/ada/adalib/gnatprj/prj-part.ali
/usr/lib/ada/adalib/gnatprj/prj-pp.ali
/usr/lib/ada/adalib/gnatprj/prj-proc.ali
/usr/lib/ada/adalib/gnatprj/prj-strt.ali
/usr/lib/ada/adalib/gnatprj/prj-tree.ali
/usr/lib/ada/adalib/gnatprj/prj-util.ali
/usr/lib/ada/adalib/gnatprj/prj.ali
/usr/lib/ada/adalib/gnatprj/restrict.ali
/usr/lib/ada/adalib/gnatprj/rident.ali
/usr/lib/ada/adalib/gnatprj/scng.ali
/usr/lib/ada/adalib/gnatprj/sdefault.ali
/usr/lib/ada/adalib/gnatprj/sfn_scan.ali
/usr/lib/ada/adalib/gnatprj/sinfo-cn.ali
/usr/lib/ada/adalib/gnatprj/sinput-c.ali
/usr/lib/ada/adalib/gnatprj/sinput-p.ali
/usr/lib/ada/adalib/gnatprj/style.ali
/usr/lib/ada/adalib/gnatprj/styleg.ali
/usr/lib/ada/adalib/gnatprj/stylesw.ali
/usr/lib/ada/adalib/gnatprj/switch-m.ali
/usr/lib/ada/adalib/gnatprj/switch.ali
/usr/lib/ada/adalib/gnatprj/targparm.ali
/usr/lib/ada/adalib/gnatprj/tempdir.ali