If src/tests/tests.sln is built instead of gyp/ANGLE.sln, the test
executable is placed under src/tests/Release*.

TEST=perf_test_runner on Windows

Change-Id: I72ce55e2caa8270bef089c073840d5e2d6caa14d
Reviewed-on: https://chromium-review.googlesource.com/438348
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>