Currently only supported on Linux. When compiled with GCC, also demangles C++ identifier names.

Should make debugging those flaky crashes on buildbots easier... :)

R=mstarzinger@chromium.org,ulan@chromium.org
BUG=

Review URL: https://codereview.chromium.org/11577019

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13222 ce2b1a6d-e550-0410-aec6-3dcde31c8c00