Integrate perlio:

[ 14618]
Nicholas Clark's tweaks to Encode compile process
1. Use decimal constants to unit string arrays rather than
very long string litterals (latter having possible "\0"
on end issues, and needing ANSI C line splicing).
2. Replace tail-recursion during insert process with itteration.
Nick C sees 12peedup from these.

p4raw-link: @14618 on //depot/perlio: de745a2ec314da23cb486732c6f7078af1fa26c6

p4raw-id: //depot/perl@14621

diff --cc ext/Encode/compile
Simple merge