RFR (L) 8171392 Move Klass pointers outside of ConstantPool entries so ConstantPool can be read-only

[Ioi Lam]

Hi,please review the following change

https://bugs.openjdk.java.net/browse/JDK-8171392
http://cr.openjdk.java.net/~iklam/jdk10/8171392_make_constantpool_read_only.v01/

*Summary:**
*
   Before:
   + ConstantPool::klass_at(i) finds the Klass from the i-th slot of 
ConstantPool.
   + When a klass is resolved, the ConstantPool is modified to store the 
Klass pointer.

   After:
   + ConstantPool::klass_at(i) finds the at this->_resolved_klasses->at(i)
   + When a klass is resolved, _resolved_klasses->at(i) is modified.


   In addition:
     + I moved _resolved_references and _reference_map from ConstantPool
       to ConstantPoolCache.
     + Now _flags is no longer modified for shared ConstantPools.

   As a result, none of the fields in shared ConstantPools are modified 
at run time,
   so we can move them into the RO region in the CDS archive.

*Testing:**
*
   - Benchmark results show no performance regression, despite the extra 
level of
     indirection, which has a negligible overhead for the interpreter.
   - RBT testing for tier2 and tier3.

*Ports:**
*
   - I have tested only the Oracle-support ports. For the aarch64, ppc 
and s390 ports,
     I have added some code without testing (it's probably incomplete)

   - Port owners, please check if my patch work for you, and I can 
incorporate your
     changes in my push. Alternatively, you can wait for my push and 
provide fixes
     (if necessary) in a new changeset, and I will be happy to sponsor it.

Thanks
- Ioi