RFR: 8159893: StringTable cleaning log line lacks the GC ID prefix

[Stefan Karlsson]

Hi all,

Please review this patch to fix the log line of the StringTable cleaning:

http://cr.openjdk.java.net/~stefank/8159893/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8159893

Before the patch:
[4.591s][debug][gc,phases,start ] GC(7) Parallel Unloading (4.591s)
[4.596s][info ][gc,stringtable  ] Cleaned string and symbol table, 
strings: 5899 processed, 0 removed, symbols: 34149 processed, 0 removed
[4.596s][debug][gc,phases       ] GC(7) Parallel Unloading (4.591s, 
4.596s) 4.902ms
[4.596s][info ][gc              ] GC(7) Pause Remark 70M->70M(20480M) 
(4.578s, 4.596s) 18.161ms

After the patch:
[4.591s][debug][gc,phases,start ] GC(7) Parallel Unloading (4.591s)
[4.596s][info ][gc,stringtable  ] GC(7) Cleaned string and symbol table, 
strings: 5899 processed, 0 removed, symbols: 34149 processed, 0 removed
[4.596s][debug][gc,phases       ] GC(7) Parallel Unloading (4.591s, 
4.596s) 4.902ms
[4.596s][info ][gc              ] GC(7) Pause Remark 70M->70M(20480M) 
(4.578s, 4.596s) 18.161ms

The TestStringSymbolTableStats test was update to match and test the new 
format.

Thanks,
StefanK