* lisp/vc/diff-mode.el (diff-setup-buffer-type): Remove "\n" from regexp.

* lisp/vc/diff-mode.el (diff-setup-buffer-type): Remove "\n" from regexp.

Remove extra "\n" from the end of the "diff --git.*" part
of 'diff-outline-regexp' because "\n" is not used in outline-regexp
and causes problems in such cases like when killing hunks
in the diff buffer with outline-minor-mode that loses
the outline icons because outline--fix-buttons-after-change and
outline--fix-up-all-buttons are limited to the single line and
can't match an outline line with a regexp that ends with "\n".

(cherry picked from commit f54b1d9f7b7a977ee4856c778a309c900ce9e8fa)