(font-lock-faces): Rename this defgroup from

(font-lock-faces): Rename this defgroup from
`font-lock-highlighting-faces'.
(font-lock-comment-face, font-lock-comment-delimiter-face)
(font-lock-string-face, font-lock-doc-face)
(font-lock-keyword-face, font-lock-builtin-face)
(font-lock-function-name-face, font-lock-variable-name-face)
(font-lock-type-face, font-lock-constant-face)
(font-lock-warning-face, font-lock-negation-char-face)
(font-lock-preprocessor-face)
(font-lock-regexp-grouping-backslash)
(font-lock-regexp-grouping-construct): Rename :group from
`font-lock-highlighting-faces' to `font-lock-faces'.