RFR (L) 8174749: Use hash table/oops for MemberName table

[coleen.phillimore at oracle.com]

Summary: Add a Java type called ResolvedMethodName which is immutable 
and can be stored in a hashtable, that is weakly collected by gc

Thanks to John for his help with MemberName, and to-be-filed RFEs for 
further improvements.  Thanks to Stefan for GC help.

open webrev at http://cr.openjdk.java.net/~coleenp/8174749.01/webrev
open webrev at http://cr.openjdk.java.net/~coleenp/8174749.jdk.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8174749

Tested with RBT nightly, compiler/jsr292 tests (included in rbt 
nightly), JPRT, jdk/test/java/lang/invoke, jdk/test/java/lang/instrument 
tests.

There are platform dependent changes in this change. They are very 
straightforward, ie. add an indirection to MemberName invocations, but 
could people with access to these platforms test this out for me?

Performance testing showed no regression, and large 1000% improvement 
for the cases that caused us to backout previous attempts at this change.

Thanks,
Coleen