bug#11617: Don't use 'register'; these days it's not needed.

[Eli Zaretskii <eliz@gnu.org>]

> From: Chong Yidong <cyd@gnu.org>
> Cc: Paul Eggert <eggert@cs.ucla.edu>,  11617@debbugs.gnu.org
> Date: Sun, 03 Jun 2012 22:50:02 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Attached is a patch to remove 'register' from the mainline
> >> Emacs source code.
> >
> > FWIW, I see no compelling reason for this change, even after I've read
> > the explanations.  This keyword is a cue to the compiler, so it in
> > general conveys non-trivial information.  If today's compilers mostly
> > ignore that, it doesn't mean this will always be the state of affairs.
> > However, by removing this, we lose those cues forever.
> 
> I wonder how many of those register variables were actually added after
> profiling to see if they make any difference.  My guess is none,
> i.e. those keywords are bogus.

??? I don't necessarily see the connection between profiling and the
keyword uses.  The way I see it, these are cues to the compiler, they
tell which of the variables are accessed in the inner loops and more
intensively, under the expected data flow.