Adjust normal runtimes for nofib along with related changes

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