Add libxkbcommon-dev to install-build-deps

We'll use this under ChromeOS ozone/freon builds for keyboard layout
support.

BUG=362698
TEST=ran install-build-deps.sh on trusty

Review URL: https://codereview.chromium.org/488833003

Cr-Commit-Position: refs/heads/master@{#290727}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@290727 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed