Use Errno more extensively so that error

Use Errno more extensively so that error
messages are more portable (another way
would be to muck around with LC_MESSAGES).
Problem reported in
To: perl5-porters@perl.org
Subject: [ID 19990719.003] LC_MESSAGES breaks h2xs autoloaded constants on AIX 4.1.4
Message-Id: <9907192239.AA44990@pcr8.pcr.com>

p4raw-id: //depot/cfgperl@3716