Integrate:

Integrate:
[ 21084]
Clean up pp_readdir() somewhat.

[ 21085]
Superparanoia.

[ 21086]
XSRETURN_UV was missing.

[ 21087]
Add Hash::Util::hash_seed() which answers among
other things the question whether our hashes are
"randomised".  (They always were...)

[ 21088]
5.8.1 was mistakenly redefining PL_sv_placeholder.
p4raw-link: @21088 on //depot/perl: e98227050ad91f6c381bce92f17cf9258b638699
p4raw-link: @21087 on //depot/perl: c910b28aed05bec7c1e3d60658ca4a270bf0077d
p4raw-link: @21086 on //depot/perl: 108ccc4560b5d414559c30fa02e7c3ad3a9302f1
p4raw-link: @21085 on //depot/perl: 16086051be220686bdbfcd84683c8399f345d235
p4raw-link: @21084 on //depot/perl: 34b7f12884b1a3cb8840062cfc8bc7369e131701

p4raw-id: //depot/maint-5.8/perl@21089
p4raw-integrated: from //depot/perl@21083 'copy in' XSUB.h (@19308..)
	lib/Hash/Util.t (@19345..) lib/Hash/Util.pm (@20688..) pp_sys.c
	(@20893..) ext/Storable/Storable.xs (@21051..) 'merge in'
	universal.c (@20224..) pod/perlrun.pod (@20674..) util.c
	(@20747..)