This is to some extent a simple transliteration of bench.sh, but also
adds some additional features:
- the ability to select which benchmarks to run, instead of having to
run all at once (via --cases option)
- help text (--help), and argument parsing
- ability to profile instruction counts (via --mode icount).
Instruction count is a stable metric, that correlates to the execution
time, but is less affected by the environment (like other heavy programs
running, or the system hardware).
Other projects (most notably rustc) use instruction count as a primary target metric.
Change-Id: I791cac499e64983efb8bcd4ea1faef13ded09ee6
eldritch horrors