Update help string for --build-dir in layout_test_wrapper.py
Update help string for --build-dir in layout_test_wrapper.py

BUG=314253

Review URL: https://codereview.chromium.org/115633003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@240821 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build