Integrate perlio:

[ 14639]
Patch up the failing multi-byte write case, and un-skip
the test.

[ 14638]
Add test for Japanese encoding (well euc-jp anyway).
Fix one bug shown by above
Skip test which does not pass yet.

[ 14637]
Split Japanese encodings - part 2
- build separate .c files with separate 'compile' steps
- overall Japanese.xs / Japanese.pm which loads them

[ 14636]
Re-structure Japanese encodings - part 1

p4raw-link: @14639 on //depot/perlio: 25f7d9d365e0d370c3b5dfc8fdfd572718a96a04
p4raw-link: @14638 on //depot/perlio: 0a95303c57acf5bd500b4d1b2412c87bb5a227e6
p4raw-link: @14637 on //depot/perlio: b90c9a30a3bfe863d14ed5fb1c105f55b9616222
p4raw-link: @14636 on //depot/perlio: 3de3d21f074d2625e0cbc46fd7d33fabf6fd811e

p4raw-id: //depot/perl@14640