[csw-maintainers] gar makepatch support

[Ben Walton]

Hi All,

I just committed r10012 that adds support for the 'makepatch' target
in GAR again.  This feature is completely reworked to use git as the
underlying mechanism for tracking changes.

You'll notice that after source extraction there is output from git as
it takes a snapshot of the pristine state of things.  Then, after each
patch (whether created with git or with diff or with...) git is used
to record the commit.

Should you subsequently make changes, you can call `gmake makepatch`
and get a new patch file stored in files/.  Patches can be generated
from any modulation (including more than one modulation per call to
makepatch).

If you find that you'd like to use git more deeply for your patch
creation, you can clone this repository externally.  To this end, I
did a few things that will make it nicer for you:

The upstream source is on the default branch 'master' and has a tag
named upstream-$(GARVERSION).  All patches are applied on a branch
named 'csw' and the final existing patch is tagged with
csw-$(GARVERSION).

Between the tags and branches, you can see differences between
upstream and each individual patch very easily.

I'll be documenting a new variable shortly as well.  This is
GIT_COMMIT_OPTS, which defaults to '-v'.  The -v will show the patch
text during the interactive commit message creation.  You can override
this with whatever you like (I use -s to get a Signed-off-by: tag, for
example).

Please let me know if you have any issues with this change.

Thanks
-Ben
-- 
Ben Walton
Systems Programmer - CHASS
University of Toronto
C:416.407.5610 | W:416.978.4302