Integrate perlio:

[  9976]
Allow $answer = encode($object,$text); like it says in docs.

[  9975]
Fix latin1 etc. alias code - (bit rot?) - the @latin2iso array now seems to need
to be in scope (fair enough), and also a package variable (our) for eval to see it.

p4raw-link: @9976 on //depot/perlio: 0f43fc9088ef519f8bd95cf48e852a436508c605
p4raw-link: @9975 on //depot/perlio: 6d6a7c8da03005f2939b162fdb831faae6901085

p4raw-id: //depot/perl@9980