[ia32] Fix for no SSE4.1.

TBR=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/645553002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24491 ce2b1a6d-e550-0410-aec6-3dcde31c8c00