Integrate perlio:

[ 13081]
Win32 layer has a dup which needs to match new prototype.

[ 13080]
Wrong way to get stdio mode used.

[ 13072]
Allow dup'ing of PerlIO::Scalar etc.

p4raw-link: @13081 on //depot/perlio: af9603a6cfcfbd30bbf18d21ddf3f61b30e8004c
p4raw-link: @13080 on //depot/perlio: 293ed4d2d77af94fb636abf7295b5e2dd98c1695
p4raw-link: @13072 on //depot/perlio: ecdeb87c58ecf41e283516bbe30cb8616ec66e13

p4raw-id: //depot/perl@13083