Integrate perlio:

Integrate perlio:

[  9604]
Split out extension finding code from buildext.pl into FindExt.pm
Use it to get Config.pm's idea of available extensions in line
with what is built.

[  9603]
Cleanup correction for failed :Via() layer, also set an error code.

[  9602]
Digests in lib/md5-file.t are for text files _without_ CRLF i.e. UNIX
style. So don't use binmode() on the handles so that Win32 etc. see
same sequence and produce same digests.

[  9601]
Allow PerlIOBase_pushed to ignore prefix on mode (e.g. sysopen's "#r")
Else it complains and so crlf layer (say) does not get pushed.

[  9599]
Quote $VERSION in Encode.pm.
regen_config_h as requested.

p4raw-link: @9604 on //depot/perlio: 8e2329934bcca9c59680f6d478c3c2bc3ef7c649
p4raw-link: @9603 on //depot/perlio: 267cbce72d0da7af102852e6d7e0bb5c1ce41da6
p4raw-link: @9602 on //depot/perlio: 9070af9fb87632d66faa82c00ab8b5cf20323a2b
p4raw-link: @9601 on //depot/perlio: c5af4229019b04c7fa4be99300f8d9883c0bdf73
p4raw-link: @9599 on //depot/perlio: b8a524e96d5b75be96d6a98368b9c29153780cfe

p4raw-id: //depot/perl@9606