Revert "Use GCC 4.7 from google"

This reverts commit 715fa03ccc044b85db4789eb8d4f9939ef94fcfd.
Revert "GCC 4.7 O3 and aliasing Optimizations"

This reverts commit 2c3ca524b4b91751a4a8af57ae68fa9b8068a6d2.