Integrate perlio:

Integrate perlio:

[ 12530]
Fixed in two places - p4 resolve

[ 12529]
Fix for ithreads/stdio build

[ 12525]
Avoid calling (now non-existant) Perl_sv_setsv(), by calling
Perl_sv_setsv_flags directly.

[ 12524]
Add a new flag character 'm' to embed.pl set to represent
"functions" which are really macros. Use it foe the troublesome
sv_setsv() etc. macros in sv.h - changing latter to define
sv_setsv rather than sv_setsv_macro etc.

[ 12523]
Add comments explaining why win32.h/embed.h are included where they are
in perl.h

[ 12522]
Code PerlIOWin32_dup - does not fix Win32 problems as :win32 is not
being used yet.

[ 12511]
Fix gross win32 build issues

p4raw-link: @12530 on //depot/perlio: ed1c0269a31901e89fe8c0090d5c6cb7881eeb2f
p4raw-link: @12529 on //depot/perlio: e0fa5af24242618e2201252ebce12dfc87892dd1
p4raw-link: @12525 on //depot/perlio: 485caab953a6ba703128628417a156139b8e7a26
p4raw-link: @12524 on //depot/perlio: af3c7592a74e7782bf0779c3272ee86140fadf53
p4raw-link: @12523 on //depot/perlio: 66a93824ccd37b2948fb857056747c3314d2a08c
p4raw-link: @12522 on //depot/perlio: aa98ed8a09f34fb745cd31d496ab825619d2c82d
p4raw-link: @12511 on //depot/perlio: a0ae667081b123207d4d0f2b6e6b7a5597859a57

p4raw-id: //depot/perl@12531