RFR(XS) : 8029070 : memory leak in jmm_SetVMGlobal

[Igor Ignatyev]

Hi all,

Please review patch (9 lines changed: 6 ins; 3 del; 0 mod)

Problem:
CommandLineFlags::ccstrAtPut copies a value and expects that caller will 
free the memory of the old value by itslef, but in jmm_SetVMGlobal, it 
doesn't do.

Fix:
Free the old value in SetVMGlobal.
The contracts of ccstrAtPut were moved to h-files.

testing: jprt
jbs: https://bugs.openjdk.java.net/browse/JDK-8029070
webrev: http://cr.openjdk.java.net/~iignatyev/8029070/webrev.00/

Thanks,
Igor