Fix unexpected quit in terminal emacs (url-retrieve-synchronously)

[mullikine]

Fixes #2417

[mullikine]

Sadly I think the while-no-input has to be placed much closer to accept-process-output.
Therefore, it's probably a bug further upstream (emacs itself). I'll attempt to raise an issue and make a PR there.

https://github.com/emacs-mirror/emacs/blob/7124598068ed267c34e1d70b49361f499fc31c9f/lisp/url/url.el#L297

            (unless (or (while-no-input
                          (with-local-quit
                            (accept-process-output proc 1)))
                        (null proc))