Android test runner: support negative gtest filter syntax.

Using --gtest_filter=-AudioInputTest.* currently results in no tests being
run, instead of "all tests except for AudioInputTest".

R=skyostil@chromium.org,cjhopman@chromium.org

Review URL: https://codereview.chromium.org/1235713003

Cr-Commit-Position: refs/heads/master@{#338396}
1 file changed