Benchmarks fail to run on GHC 7.10.3

[RyanGlScott]

Originally discovered here: iu-parfunc/sc-haskell#7. Note that this is run when cryptol is obtained from Hackage (i.e, through cabal get or stack unpack):

Benchmark cryptol-bench: RUNNING...
benchmarking parser/Prelude
time                 220.9 μs   (220.5 μs .. 221.3 μs)
                     1.000 R²   (1.000 R² .. 1.000 R²)
mean                 223.8 μs   (222.5 μs .. 228.9 μs)
std dev              7.782 μs   (1.010 μs .. 16.39 μs)
variance introduced by outliers: 31% (moderately inflated)

cryptol-bench: bench/data/BigSequence.cry: openFile: does not exist (No such file or directory)
Benchmark cryptol-bench: ERROR

For some reason, bench/data/BigSequence.cry isn't distributed with the tarball when gathered up via cabal sdist.

[RyanGlScott]

I believe #333 fixes this.

[acfoltzer]

Thanks, Ryan!