Integrate:

Integrate:
[ 22517]
Subject: malloc wrappage
Message-Id: <37BF70DE-5C0E-11D8-B5A1-00039362CB92@iki.fi>

plus change croak to Perl_croak_nocontext to make ithread safe
plus make it conditional on PERL_MALLOC_WRAP (default for blead is on)

[ 22524]
Try to fix the AIX and Windows builds regarding the
definedness of the PL_memory_wrap symbol.

[ 22526]
Detypo.

[ 22571]
Make usemallocwrap a Configure-time question. Default is yes for
usedevel, no otherwise, but I'm expecting hints files on known
good platforms to override this. (and known bad)
Demonstration hints file for darwin.

[ 22576]
Export PL_memory_wrap based on PERL_MALLOC_WRAP rather than
NO_MALLOC_WRAP following Configure changes. Identical patch to
mine supplied by Steve Hay while I was working on this.
IP shootout at dawn :-)

[ 22577]
Unlike perl, 0 in void context isn't special cased in C :-)
(So it warns). Tweak the no-action malloc wrap checkers to avoid
warnings.
p4raw-link: @22577 on //depot/perl: 410319be38cf59e3f4abf4e02ad9f57622d4d2d5
p4raw-link: @22576 on //depot/perl: 210c4a3d4af9a86fc2ee7906a6a02d684efd3baa
p4raw-link: @22571 on //depot/perl: 9df442c23deb1b1ba2f163eb54deeb4fe82ea80c
p4raw-link: @22526 on //depot/perl: 3f3908796fa800fe68872cec2bbd5da4cfc02ec5
p4raw-link: @22524 on //depot/perl: 57185c71ec028665c77b9bdf20d9fb51d8458287
p4raw-link: @22517 on //depot/perl: 27d5b266d3ace9bd49a167d34f7350f3768d1326

p4raw-id: //depot/maint-5.8/perl@22583
p4raw-integrated: from //depot/perl@22581 'copy in' handy.h (@22517..)
	'edit in' perl.h (@22563..) 'merge in' av.c (@19268..)
	hints/darwin.sh (@21520..) config_h.SH (@22334..) Configure
	(@22379..)
p4raw-integrated: from //depot/perl@22524 'edit in' makedef.pl
	(@22032..)
p4raw-integrated: from //depot/perl@22517 'merge in' pod/perldiag.pod
	(@22437..) pp.c (@22509..)