directory specified, and add it to sysIncPath only if it exists.
However, afterwards make tested for the presence of a -m option by
checking to see if sysIncPath was an empty list, and assumed that
the -m option was not used if it was empty. This obviously breaks
if -m specified a non-existent directory. So I have added a flag
that is set if the -m option is used, and I test that instead.