Drop unused and undocumented dummy_ from SaveContext.

Also remove the obsolte __GNUC_VERSION__ #define.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/23522003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16385 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Fix accidential inclusion of <intrin.h> into namespace v8::internal.

Also cleanup the fallback __cpuid() implementation, and add
a comment about preserving the GOT pointer in case of PIC.

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/23464014

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16386 ce2b1a6d-e550-0410-aec6-3dcde31c8c00