Runtime for nofib benchmarks was all over the place.
This patch adjusts runtime for most benchmarks such
that it falls into the 0.2-2s range.

This means that:
* A default run will take longer
* Time spent will be better distributed among benchmarks.
* More benchmarks have runtimes long enough to be used
  for runtime analysis.

Some more changes were done which go hand in hand
with changing runtimes.
* Some benchmarks now create their input files during boot.
* Moved input files for anna in their own directory.
* Remove printing of output for some of the floating
  point heavy benchmarks.
* Added a comment about desired runtimes to README.
* Made grep actually benchmark something.
* Throw cachgrind out of the default benchmarks.
  The nondeterministic behaviour has been an issue for a
  while and it doesn't seem like an essential benchmark.

Test Plan: run nofib in modes slow/normal/fast

Reviewers: O26 nofib, alpmestan

Reviewed By: alpmestan

Subscribers: sgraf, alpmestan

Differential Revision: https://phabricator.haskell.org/D4989