Integrate perlio:

Integrate perlio:

[ 13854]
Win32 and makedef.pl fall-out of PerlIO/pTHX stuff

[ 13853]
Put PerlIO stuff inside EXTERN C

[ 13852]
Add at least the "important" PerlIO_xxxx functions to embed.pl
so that they get implicit pTHX_ and we can avoid slow dTHX.

p4raw-link: @13854 on //depot/perlio: 3da9a137807e4f1acaf9cb3024a6cc5fbd119b9f
p4raw-link: @13853 on //depot/perlio: 582ed04c91818c6c9bf5b51c84f67b7c565925a7
p4raw-link: @13852 on //depot/perlio: e87a358ade5a3dd9a8b192569e18211d76c93743

p4raw-id: //depot/perl@13862