/usr/lib/pkgconfig/antlr-cil.pc is in libantlr2.7-cil 2.7.7+dfsg-6ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/pkgconfig/antlr-cil-2.7.pc
/usr/lib/pkgconfig/antlr-cil-2.7.pc