emacs: Set indent-tabs-mode in perl-mode

This matches existing practice, but makes the setup complete and
consistent with the C code setup.

.dir-locals.el

@@ -13,6 +13,7 @@
                (perl-brace-offset . 0)
                (perl-brace-imaginary-offset . 0)
                (perl-label-offset . -2)
+               (indent-tabs-mode . t)
                (tab-width . 4)))
  (sgml-mode . ((fill-column . 78)
                (indent-tabs-mode . nil))))

src/tools/editors/emacs.samples

@@ -51,6 +51,7 @@
   (setq perl-continued-statement-offset 4)
   (setq perl-indent-level 4)
   (setq perl-label-offset -2)
+  (setq indent-tabs-mode t)
   (setq tab-width 4))
 
 (add-hook 'perl-mode-hook