Summary: This diff adds an `.hgignore` file for the `linelog` directory.
Test Plan: `make local`, and run `hg status`, make sure no unwanted files are printed.
Reviewers: #mercurial, ttung, akushner
Reviewed By: akushner
Subscribers: mjpieters
Differential Revision: https://phabricator.intern.facebook.com/D3699575
Signature: t1:3699575:1471151389:7e4de7b75d671d3f0db18337e57c65e9972de059
