Add export_v8_tarball.py, a new tool to also export standalone tarballs for V8.
Add export_v8_tarball.py, a new tool to also export
standalone tarballs for V8.

This will be useful for Linux distributions packaging
shared library packages for V8.

BUG=none

Review URL: http://codereview.chromium.org/7600011

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@96099 0039d316-1c4b-4281-b951-d872f2087c98

gavinp/chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,yitian134/chromium,yitian134/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,ropik/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,adobe/chromium