Silence dpkg-query errors in install-build-deps.
Silence dpkg-query errors in install-build-deps.

On leading-edge Ubuntu versions there are no LTS backport packages, and
dpkg-query prints an error about nothing matching the wildcard to
stderr, which has caused at least one user to think the script didn't
install mesa correctly. The script handles this case just fine, though
(it expands to an empty array and sets mesa_variant to emptystring,
whcih is correct), so just redirect stderr to avoid this spurious error
message.

BUG=

Review URL: https://codereview.chromium.org/1721763003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#377332}

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