bug#33567: Syntactic fontification of diff hunks

[Juri Linkov]

> Anyway, to be clear, and other considerations aside, this works:
>[...]
>  (defface diff-added
> @@ -315,9 +313,7 @@ diff-added
>      (((class color) (min-colors 88) (background light))
>       :background "#ddffdd")
>      (((class color) (min-colors 88) (background dark))
> -     :background "#335533")
> -    (((class color))
> -     :foreground "green"))
> +     :background "#335533"))
>    "`diff-mode' face used to highlight added lines.")
>[...]
>  (defface diff-indicator-added
>    '((default :inherit diff-added)
>      (((class color) (min-colors 88))
> -     :foreground "#22aa22"))
> +     :foreground "#22aa22")
> +    (((class color))
> +     :foreground "green"))
>    "`diff-mode' face used to highlight indicator of added lines (+, >)."
>    :version "22.1")
>  (defvar diff-indicator-added-face 'diff-indicator-added)

This looks good.

For the same reason we have the face font-lock-comment-delimiter-face
separate from font-lock-comment-face to use colors only on the former,
but not on the latter on tty with 8 colors to make easier to read comments.