RFR 8161445: [BACKOUT] MemberNameTable doesn't purge stale entries

[Coleen Phillimore]

Summary: Original change caused performance regression in 
microbenchmarks after GC

Eric Caspole's additional performance measurements are in the bug 
report.  Also, I don't think it was a good idea for the jvm to intern 
MemberName assuming they are immutable.   The interning should be in 
Java code.  I didn't see a huge advantage to interning these as there 
weren't a big proportion of duplicates that I could see in my logging.  
I added a REDO bug and contacted the submitter for the severity of this 
problem in real life, since what they sent was a microbenchmark as well.

Tested with JPRT and original test case.  The backout was clean and had 
no conflicts.

open webrev at http://cr.openjdk.java.net/~coleenp/8161445/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8161445

Thanks,
Coleen