Test landmines.

BUG=
R=jochen@chromium.org
TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/415533003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22560 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Add tsan support to v8's gyp and test driver.

Tests only the default variant for now.

BUG=
R=jochen@chromium.org

Review URL: https://codereview.chromium.org/412853002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22561 ce2b1a6d-e550-0410-aec6-3dcde31c8c00