EMACS=t Joy and Happiness

[phillip.lord@russet.org.uk (Phillip Lord)]

Well, it hardly seems like Mon, 11 Apr 2016 since last we discussed this
issue.

If you remember, we managed to blitz, EMACS=t everywhere, then Paul
restored it in term.el because it broke bash otherwise. master currently
looks like this:

  ;; This is for backwards compatibility with Bash 4.3 and earlier.
  ;; Remove this hack once Bash 4.4-or-later is common, because
  ;; it breaks './configure' of some packages that expect it to
  ;; say where to find EMACS.
  (format "EMACS=%s (term:%s)" emacs-version term-protocol-version)

I worry that "Bash 4.4 or later is common" is rather indeterminate; my
desktop is now 4.4.19. but another machine I am using has bash
4.2.46. Given that Emacs-26 is now destined to come out with
EMACS=26.1.0, I would like to propose that we now remove this on master,
i.e. make it happen for Emacs-27 which should be in about 2020.

Phil