Integrate:

Integrate:
[ 22830]
[perl #29637] Thread creation time is hypersensitive

Due to a logic error, the dup ptr table sometimes wans't being
grown, leading to extremely slow cloning.

[ 22831]
improve hashing algorithm for ptr tables in perl_clone:
the bottom few bits of a pointer are usually zero
p4raw-link: @22831 on //depot/perl: 134ca3d6c0df26ae21f9d33f6fbf207fca26b857
p4raw-link: @22830 on //depot/perl: 14cade97ead1fce5346533c9ffae161becee82db

p4raw-id: //depot/maint-5.8/perl@22860
p4raw-integrated: from //depot/perl@22831 'edit in' sv.c (@22830..)