Ok ... the module built fine with perl 5.6. So if you take the exact same source that worked with 5.6 and try to build with perl 5.8, it fails ... right ? (There are exceptions, but you would generally expect that source code that compiles with 5.6 would also compile with 5.8.)
That could be the case (especially if 'perl -V:cc' returns "cc='gcc';"). What does 'perl -V:cc' return ?