Revert "More libcorkscrew fixes for GCC 4.8+"

This reverts commit 1d9ded2dae6dc163fc38239aad853d3d3c5fe221.
Revert "corkscrew: Fix build with gcc 4.8+"

This reverts commit cc31d9f76cd0dae5fa5d11d9f56bc86443bfad4e.
Revert "Add __attribute__((unused)) for unused parameters"

This reverts commit 90247ec9085aa8f2787de0377e846e3e2b7ff5bf.