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)

sh: Get rid of unnecessary non-standard empty lists.

POSIX does not allow constructs like:
if cmd; then fi
{ }
Add a colon dummy command, except in a test that verifies that such empty
lists do not cause crashes when used as a function definition.

Add tests for r193169.

- Add tests for hash and return and more tests for set -e.
- Simplify regress.sh, sort tests.

Simplify and add PR 77067 which addresses the same bug.

Fix syntax error that crept in somehow.

Add a couple of regression tests for /bin/sh.