Make benchmarks compile with modern criterion

[RyanGlScott]

I had to do some minor code changes to make things work, including sprinkling whnfIO in various places (since the type of bench changed in criterion-1) and avoiding the use of the b function with mpMask/mask, since there were some type inference issues involving RankNTypes.

Fixes #29.

[basvandijk]

Thanks and sorry for the long delay. Released as 0.2.3.7.

[RyanGlScott]

Thanks! There's also basvandijk/case-insensitive#21 if you feel like fixing more benchmarks ;)

[basvandijk]

Sure, I will probably have some time for it on ZuriHac.