[8u] RFR 8155951 & 8151066

[Zhengyu Gu]

Please review following backports:

8155951: VM crash in nsk/jvmti/RedefineClasses/StressRedefine: assert
           failed: Corrupted constant pool
https://bugs.openjdk.java.net/browse/JDK-8155951

8151066: assert(0 <= i && i < length()) failed: index out of bounds
https://bugs.openjdk.java.net/browse/JDK-8151066

Original jdk9 patch contains both fixes and they are all on Oracle 8u 
backport list.

The patch does not apply cleanly. Other than a few minor conflicts, e.g. 
copyright years, breaking single line long parameter list to multi-lines 
and line shifts, jdk8u lock declaration  (def macro in mutexLocker.cpp) 
does not take 5th argument.

JDK9 code review thread: 
https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2016-May/019476.html

8u backport: 
http://cr.openjdk.java.net/~zgu/JDK-8155951-8u/webrev.00/index.html

Thanks,

-Zhengyu