Revert "removed c2hs dependency"

This reverts commit cc0d0102d000ac0274e01cfd48c8d45260d3f9df.
Revert "remove dep on c2hs (TODO: cleanup generated hs files and remove chs files)"

This reverts commit 8b0516ab03666abcaa0c3cd7e863c4417e5cd4b6.