Perl which ships with solaris 10 is ancient. I can replicate your problem with this version. I always leave the system perl alone. I'd guess either there's something that the version of ExtUtils::MakeMaker the system perl is using doesn't understand the LICENSE paramater, or there's something wrong with perl 5.8.4, though ExtUtils::MakeMaker seems more likely to me.

I tend to build a modern version of perl elsewhere (/opt/blah/perl or something sensible), leaving the system perl alone (Solaris uses this for various system bits and bobs). My advice would be to do this, rather relying on a perl from 8 years ago. There have been many improvements :)