Make Emacs perl-mode indent more like perltidy.

This especially helps braces that surround code blocks.  Back-patch to
v11, where commit 56fb890 first
appeared; before that, settings were even more distant from perltidy.

Reviewed by Andrew Dunstan.

Discussion: https://postgr.es/m/20190103055355.GB267595@gust.leadboat.com

.dir-locals.el

@@ -9,7 +9,7 @@
                (indent-tabs-mode . nil)))
  (perl-mode . ((perl-indent-level . 4)
                (perl-continued-statement-offset . 2)
-               (perl-continued-brace-offset . 4)
+               (perl-continued-brace-offset . -2)
                (perl-brace-offset . 0)
                (perl-brace-imaginary-offset . 0)
                (perl-label-offset . -2)

src/tools/editors/emacs.samples

@@ -47,10 +47,13 @@
   (interactive)
   (setq perl-brace-imaginary-offset 0)
   (setq perl-brace-offset 0)
-  (setq perl-continued-brace-offset 4)
   (setq perl-continued-statement-offset 2)
+  (setq perl-continued-brace-offset (- perl-continued-statement-offset))
   (setq perl-indent-level 4)
   (setq perl-label-offset -2)
+  ;; Next two aren't marked safe-local-variable, so .dir-locals.el omits them.
+  (setq perl-indent-continued-arguments 4)
+  (setq perl-indent-parens-as-block t)
   (setq indent-tabs-mode t)
   (setq tab-width 4))