Add new options to mini-benchmark.sh so it is more useful, such as
`--log` to avoid output from `lscpu` and other commands being lost.

Also fix following errors:

- Fix if condition for the cycle count regression verdict. The condition
  checked if the cycle count was greater than 850 billion, but `$RESULT`
  is only 3 digits and represents the number of cycles in billions.

- Fix flamegraph width. The original width caused the flamegraph to be
  cut-off on most screen sizes in the browser.

- Fix ShellCheck warnings and suggestions.

- Fix condition to check if perf has permission to run on the system.

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services, Inc.