* test/lisp/vc/diff-mode-resources/git.patch: Delete file, moving
its contents to...
* test/lisp/vc/diff-mode-tests.el (diff-mode-tests--git-patch):
...this new variable. Git merges kept deleting a trailing
whitespace in the patch signature, so let's do this instead.
(diff-mode-test-git-patch)
(diff-mode-test-git-patch/before-first-hunk)
(diff-mode-test-git-patch/signature): Use above new variable.
* lisp/vc/diff-mode.el (diff-font-lock-keywords): Don't fontify lines in
Git patches starting with + or - as added/removed, if they are either
before the first hunk, or in the email signature. (Bug#75884)
(diff-buffer-type): Move definition up.
(diff--indicator-added-re, diff--indicator-removed-re): New variables.
(diff--git-preamble-end, diff--git-footer-start)
(diff--indicator-matcher-helper, diff--indicator-added-matcher)
(diff--indicator-removed-matcher): New functions.
* test/lisp/vc/diff-mode-tests.el (diff-mode-test-git-patch)
(diff-mode-test-git-patch/before-first-hunk)
(diff-mode-test-git-patch/signature): New tests.
* test/lisp/vc/diff-mode-resources/git.patch: New file.
