classes/patch: move in logic to commit for additional tasks

classes/patch: move in logic to commit for additional tasks

If PATCHTOOL is "git", and PATCH_COMMIT_FUNCTIONS is set to "1", for
additional tasks between do_unpack and do_patch, make a git commit. This
logic was previously implemented in devtool itself, but it makes more
sense for it to be implemented in the patch class since that's where the
rest of the logic is for this (or in lib/oe/patch.py). It also makes
it possible for this to work with tinfoil2.

(From OE-Core rev: f24f59ea1d8bc335ea8576f6a346d0935f4a3548)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>