- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Import m4 regression tests from OpenBSD

Obtained from: OpenBSD
Approved by: des (mentor)

I explicitly meant to not move any of this over to the new m4(1) framework,
even slightly. Grrr CVS.

Move all remaining tests except for:
make(1): Does not work like the other tests. Its Makefile is
self-testing.
m4(1): It uses complex voodo to test GNU m4(1) features.

To the new framework. I had worried about passing the binary data that
uudecode(1)'s test passes to diff(1) might give a user something nasty,
but this is unlikely to happen as even with an unmodified old nasty
diff(1) which doesn't recognise many binary files, these binary files
are recognised. Using $DIFF instead of `diff' in the library and making
it possible to override this with `cmp -s' might be nice some day, but
as of this second, there's no immediate need.

Add a regression test for m4(1).

This checks the behaviour of changecom() in both GNU and BSD modes of our m4.