Improve V8 VFPv3 runtime detection, to address issue 914.

This patch will check for the exact word vfpv3 as well as 0xc08 (CortexA8
part number) as some earlier kernel didn't report vfpv3 for A8.

Codereview URL: http://codereview.chromium.org/4103013/show

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5751 ce2b1a6d-e550-0410-aec6-3dcde31c8c00