Integrate perlio:

[ 10843]
Back out debug in taint.t

[ 10841]
Skip cwd test on Win32 ???

[ 10836]
Skip |- based op/write.t on Win32 as well as VMS

p4raw-link: @10843 on //depot/perlio: 368417138e099f70714a4b8804e7d16d31d19316
p4raw-link: @10841 on //depot/perlio: 004cc5080f573783a512f0d3ef678c4e019ac166
p4raw-link: @10836 on //depot/perlio: 7da144458ae5f3165669e6f0a8f2562715984328

p4raw-id: //depot/perl@10844