(insert-file-contents-as-raw-text): Return value.

(insert-file-contents-as-raw-text): Return value.
(encode-coding-string): Check `coding-system' is non-nil.
(decode-coding-string): Ditto.
(insert-file-contents-as-binary): Use `as-binary-input-file'.
(insert-binary-file-contents-literally): Ditto.
(write-region-as-binary): Use `as-binary-output-file'.
(write-region-as-raw-text-CRLF): Definition for Emacs 19.28.
(write-region-as-mime-charset): Ditto.
(mime-charset-to-coding-system): New implementation.
(ccl-use-symbol-as-program): New constant.
(ccl-encoder-eof-block-is-broken): New constant.
(ccl-decoder-eof-block-is-broken): New constant.
(ccl-eof-block-is-broken): New constant.
(make-ccl-coding-system): New function.
(ccl-execute): Emacs 20.3 emulating function.
(ccl-execute-on-string): Emacs 20.3 emulating function.