Remove lisp/erc/ file-local indent-tabs-mode settings

Remove lisp/erc/ file-local indent-tabs-mode settings

* lisp/erc/erc-autoaway.el:
* lisp/erc/erc-backend.el:
* lisp/erc/erc-button.el:
* lisp/erc/erc-compat.el:
* lisp/erc/erc-dcc.el:
* lisp/erc/erc-fill.el:
* lisp/erc/erc-ibuffer.el:
* lisp/erc/erc-identd.el:
* lisp/erc/erc-imenu.el:
* lisp/erc/erc-join.el:
* lisp/erc/erc-list.el:
* lisp/erc/erc-log.el:
* lisp/erc/erc-match.el:
* lisp/erc/erc-menu.el:
* lisp/erc/erc-netsplit.el:
* lisp/erc/erc-networks.el:
* lisp/erc/erc-notify.el:
* lisp/erc/erc-page.el:
* lisp/erc/erc-pcomplete.el:
* lisp/erc/erc-replace.el:
* lisp/erc/erc-ring.el:
* lisp/erc/erc-services.el:
* lisp/erc/erc-sound.el:
* lisp/erc/erc-speedbar.el:
* lisp/erc/erc-stamp.el:
* lisp/erc/erc-track.el:
* lisp/erc/erc-truncate.el:
* lisp/erc/erc-xdcc.el:
* lisp/erc/erc.el: Remove indent-tabs-mode setting, so that we follow
Emacs' global indent-tabs-mode=nil setting (and much of the
indentation in these fails is already spaces anyway).  Also remove
tab-width=8 settings, since those are redundant with the setting in
the top-level .dir-locals.el.