Improve install-build-deps mesa handling.
Improve install-build-deps mesa handling.

Instead of hardcoding a list of which LTS variants of mesa might be
installed, just query for any package that matches the expected pattern
and if exactly one is installed, use that. If zero are installed, use
the base package. There shouldn't be more than one as these packages
conflict with each other, so just abort if that happens.

This avoids needing to extend the loop in this script every time a new
Ubuntu backport package is added.

BUG=

Review URL: https://codereview.chromium.org/1434453002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#358039}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk