RFR(S): 8240204: Optimize package handling for archived classes

[Yumin Qi]

Hi,

   Please review:
   bug: 8240204: https://bugs.openjdk.java.net/browse/JDK-8240204
   webrev: http://cr.openjdk.java.net/~minqi/8240204/webrev-01/

   Summary: Move ClassLoader::add_package to InstanceKlass since what it 
does is calling pkg->set_classpath_index. Also a minor optimization for 
InstanceKlass::set_package, for shared class, avoid call 
check_prohibited_package since CDS does not archive prohibited classes.

   Tests: hs-tier1-4
   Performance data: javac and zprint showed a little improvement.

   Thanks
   Yumin