(pp-fill): Cut before parens and dots

(pp-fill): Cut before parens and dots

The `pp-fill` code sometimes end up generating things like:

    (foo .
         bar)

instead of

    (foo
     .  bar)

so make sure we cut before rather than after the dot (and open
parens while we're at it).

* lisp/emacs-lisp/pp.el (pp-fill): Cut before parens and dots.

* test/lisp/emacs-lisp/pp-tests.el (pp-tests--dimensions): New function.
(pp-tests--cut-before): New test.

(cherry picked from commit 7269a2f1586733bd03b569608bd77112b2e6487f)