Revert "Add strict_aliasing."

This reverts commit 4d318bade28d6b7027c62699d923b99c2119fad5.
Revert "GCC 4.7 O3 and aliasing Optimizations"

This reverts commit 1bb5c2f3ce324be2e17c6f69eff3c574ffe1e4fc.
Revert "Use GCC 4.7 from google"

This reverts commit e8d6ddbdefdefc314bc843f05a983c3bf9c54334.