bug#12242: Emacs 24.2 RC1 build fails on OpenBSD

[Eli Zaretskii <eliz@gnu.org>]

> From: Chong Yidong <cyd@gnu.org>
> Cc: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>,  Stefan Monnier <monnier@iro.umontreal.ca>,  Kenichi Handa <handa@m17n.org>,  jca@wxcvbn.org,  12242@debbugs.gnu.org
> Date: Thu, 23 Aug 2012 22:24:19 +0800
> 
> Let us consider outright reversion of 108048.  What would be the effect?
> Given a choice between a bug (Bug#11519) which is also in 24.1, and
> failure-to-compile on OpenBSD as a new regression, the former is far
> preferable, unless you can point out some consequence that is more
> serious that the discussion in Bug#11519 implies.

Reverting 108048 (and 108020, see below) will cause trouble to any
system that uses ralloc.c, including (evidently) OpenBSD.  The fact
that the problem was originally found only during bootstrap on Windows
is just a coincidence.  It can strike at any time that regexp search
is used in a text that includes characters which need unification.
It's a bomb waiting to explode.  So I don't recommend that.

Of course, Emacs 24.1 was shipped with that bug, so ...

Can I have a 1-day grace to try debugging the OpenBSD crash?  Jérémie
generously gave me a login on the machine where it happened, and I'd
like a chance to try debugging it.

> Also, if we revert 108048, should we revert 108020 (which is in 24.1) as
> well?  Could you explain what problem 108020 causes which 108048 is
> supposed to fix?  Does it have symptoms?

108020 had a logic flaw in the incrementing and decrementing the flag
that inhibits relocation.  Due to that flaw, the inhibition was not
really working beyond the first time.  108048 fixed that part.  And
yes, these two revisions go together.