Integrate perlio:

[  8498]
Encode cleanup.
Add command line control over "compile" so that Makefile.PL
needs can be combined with other uses.
Use command line options in Makefile.PL.
Fix multi-byte parsing in .ucm files.

[  8497]
Warn and set errno when open(...,":encoding(xxxxx)",...) cannot find xxxxx.

[  8496]
Fixup after integrate:
missed the .sym files that are changed by regen_headers
sv.c and proto.h disagreed about pTHX_ ness of EXPECT_NUMBER.

[  8484]
Infrastructure to allow:
open($fh,"|-",@array);
to be implemented
i.e. mark pp_open as needing a stack mark, and make pp_open
process its args in that style (and pass them _all_ to tied handles OPEN).
Invent do_openn() which takes SV ** at allow it to see multiple args.
Note this does not _do_ anything yet.

p4raw-link: @8498 on //depot/perlio: afdae191a418d1363d2ddc3dcefffb0785c0a155
p4raw-link: @8497 on //depot/perlio: 52744f63cab71e4f408a2490707f42c331bb389e
p4raw-link: @8496 on //depot/perlio: 9dd79c3f9b66ee5059b4277b6f15d5bfcd846510
p4raw-link: @8484 on //depot/perlio: a567e93b903bc9849952c06533059c2f2e2fb226

p4raw-id: //depot/perl@8500

diff --cc sv.c
Simple merge