Fraser Tweedale authored May 12, 2022 and Marge Bot committed May 26, 2022

executablePath support for NetBSD was added in
a172be07, but the test was not
updated.

Update the test so that it works for NetBSD.  This requires handling
some quirks:

- The result of getExecutablePath could include "./" segments.
  Therefore use System.FilePath.equalFilePath to compare paths.

- The sysctl(2) call returns the original executable name even after
  it was deleted.  Add `canQueryAfterDelete :: [FilePath]` and
  adjust expectations for the post-delete query accordingly.

Also add a note to the `executablePath` haddock to advise that
NetBSD behaves differently from other OSes when the file has been
deleted.

Also accept a decrease in memory usage for T16875.  On Windows, the
metric is -2.2% of baseline, just outside the allowed ±2%.  I don't
see how this commit could have influenced this metric, so I suppose
it's something in the CI environment.

Metric Decrease:
    T16875