Gnus: fix article to always display git diffs properly

[Luis Henriques <henrix@camandro.org>]

Hi!

It's been a while since I realised that some emails containing inline
patches generated with git aren't actually recognised as such in Gnus.
And today I finally decided to figure out why.  Basically, it's because it
is assumed that those patches will end with a signature -- and that's not
always true.

Below there's a one-liner that seems to fix it -- it's not thoroughly tested,
but nothing seems to break.  Note that the other diff elements don't have
an 'end-point' either.  Would this change be acceptable?

(And also note that the patch does *not* have a signature at the end!)

Cheers,
-- 
Luís

diff --git a/lisp/gnus/mm-uu.el b/lisp/gnus/mm-uu.el
index 3c7e3cbdf1af..f5d553bd0892 100644
--- a/lisp/gnus/mm-uu.el
+++ b/lisp/gnus/mm-uu.el
@@ -173,7 +173,7 @@ mm-uu-type-alist
      ,#'mm-uu-diff-test)
     (git-format-patch
      "^diff --git "
-     "^-- "
+     nil
      ,#'mm-uu-diff-extract
      nil
      ,#'mm-uu-diff-test)