Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

rs: Test actual output in the tests.

Previously the tests just verified if command line arguments raised an
error or not, they did not test how command line arguments affected
the output. This adds some sample (if simple) input and output to
each flag test as well as adding a few additional trivial tests.

Reviewed by: brooks
Differential Revision: https://reviews.freebsd.org/D36835

rs: Use getopt() and strtol() instead of mannual parsing.

This uses the "::" extension to getopt() to handle options which take
an optional argument.

The updated flag tests were all wrong before and only passed because
the manual parser failed to raise errors when a required argument was
missing. The invalid argument test now gets a better error message.

Reviewed by: brooks, imp, emaste
Differential Revision: https://reviews.freebsd.org/D36834

Add basic tests for ctfconvert(1), fold(1) and rs(1)

Add basic command line parsing test coverage for these utilities. The tests
were automatically generated based on their man pages. These tests can be
expanded by hand for more thorough coverage. The aim is to generate very
basic amount of test coverage for all the utilities in the base system.

Tests generated via: https://github.com/shivansh/smoketestsuite/

Submitted by: shivansh
Reviewed by: asomers
MFC after: 3 weeks
Differential Revision: https://reviews.freebsd.org/D12424