Add LTO support for Android Chromium.

This is to add support for a Link-Time Optimizations experiment in Android Chromium. As it is disabled by default, it won't change anything for most configurations.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/497713002

Patch from Fabrice de Gans <fdegans@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23336 ce2b1a6d-e550-0410-aec6-3dcde31c8c00