Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Expand / correct newsyslog regression tests:
- Test newslog with clasic naming of rotates files to actually test
the correct number of log files as newsyslog now does the correct
thing post r220926.
- Add some more newsyslog tests which tests keeping 0, 1, and 2
logfiles.

Add regression tests for newsyslog. These are far from a complete
test of newsyslog, as they were mainly made to test 'newsyslog -t',
but they do test the basic functionality.

The test 'framework' was based on dds@'s code in
src/tools/regression/bin/mv/.

Note that currently these tests are not fully correct for the
non-timestamp based rotation case, as it seems like newsyslog actually
by default keeps a file too much around.

MFC after: 3 weeks