Integrate perlio:
Jarkko Hietaniemi [Sun, 18 Feb 2001 17:15:39 +0000 (17:15 +0000)]
[  8820]
Clean up a few core dumps when layers are used in unexpected ways.
(Still not "right"...)

p4raw-link: @8820 on //depot/perlio: 26fb694e6e6fd977f3c75086486e1c4578925875

p4raw-id: //depot/perl@8825


Trivial merge