Remove $FreeBSD$: one-line sh pattern

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

Merge ^/user/ngie/release-pkg-fix-tests to unbreak how test files are installed
after r298107

Summary of changes:

- Replace all instances of FILES/TESTS with ${PACKAGE}FILES. This ensures that
namespacing is kept with FILES appropriately, and that this shouldn't need
to be repeated if the namespace changes -- only the definition of PACKAGE
needs to be changed
- Allow PACKAGE to be overridden by callers instead of forcing it to always be
`tests`. In the event we get to the point where things can be split up
enough in the base system, it would make more sense to group the tests
with the blocks they're a part of, e.g. byacc with byacc-tests, etc
- Remove PACKAGE definitions where possible, i.e. where FILES wasn't used
previously.
- Remove unnecessary TESTSPACKAGE definitions; this has been elided into
bsd.tests.mk
- Remove unnecessary BINDIRs used previously with ${PACKAGE}FILES;
${PACKAGE}FILESDIR is now automatically defined in bsd.test.mk.
- Fix installation of files under data/ subdirectories in lib/libc/tests/hash
and lib/libc/tests/net/getaddrinfo
- Remove unnecessary .include <bsd.own.mk>s (some opportunistic cleanup)

Document the proposed changes in share/examples/tests/tests/... via examples
so it's clear that ${PACKAGES}FILES is the suggested way forward in terms of
replacing FILES. share/mk/bsd.README didn't seem like the appropriate method
of communicating that info.

MFC after: never probably
X-MFC with: r298107
PR: 209114
Relnotes: yes
Tested with: buildworld, installworld, checkworld; buildworld, packageworld
Sponsored by: EMC / Isilon Storage Division

Add missing shebang

Plain test programs are not preprocessed by the build system (as opposed to
ATF test cases, which automatically gain a shebang pointing at atf-sh), so
we must take care of providing the shebang ourselves.

I'm not sure why this was not causing problems with Kyua 0.11, but the
upcoming 0.12 release chokes on this particular issue.

MFC after: 1 week

Generate plain sh test programs from a source file.

Instead of assuming that plain sh test programs exist in the source
tree in their final form and are marked as executable, generate them
from a list of sources.

By default, just assume that the source file for a program P is P.sh
but allow the caller to customize the inputs. Similarly, also allow
the caller to apply sed(1) replacements on the output. These will
both be useful in hooking existing test code from tools/regression/
into the test suite.

Approved by: rpaulo (mentor)