Original message: Implement committed physical memory stats for Linux.
This had to be reverted because it crashes when compiled into Chromium
due to the sandbox not allowing the mincore call.

R=verwaest@chromium.org
BUG=v8:2191

Review URL: https://codereview.chromium.org/11023010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12640 ce2b1a6d-e550-0410-aec6-3dcde31c8c00