Fix perl build on Digital UNIX after JDK installs libnet.so

Fix perl build on Digital UNIX after JDK installs libnet.so

Subject: [PATCH] Perl & JAVA co-existence

It turns out that the JDK on Digital UNIX installs a libnet.so
which gets in the way when building Perl.  Back during 5.003_28,
I didn't do anything to remove libnet because there wasn't one,
but now there can be a libnet, and it's wrong.  So, here's a
patch to the dec_osf hints file to skip libnet as well as some of
the others we're already ignoring.

p5p-msgid: 199709191826.OAA18040@Orb.Nashua.NH.US