This file is indexed.

/lib/modules/4.4.0-121-lowlatency/build is in linux-headers-4.4.0-121-lowlatency 4.4.0-121.145~14.04.1.

This file is owned by root:root, with mode 0o777.

It is a symlink to /usr/src/linux-headers-4.4.0-121-lowlatency