RFR: JDK-8141045: Remove SPARSE_PRT_VERBOSE from the G1 code

[Bengt Rutisson]

Hi everyone,

Another define that guards debugging code.

http://cr.openjdk.java.net/~brutisso/8141045/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8141045

The SPARSE_PRT_VERBOSE define is used in the code to log more detailed 
information about the marking cycle. Since this is a define that 
requires re-compilation to have any effect the code is not used by 
normal builds.

Thus, this is to be considered debug code. As such it should be removed 
from the normal code base and included back if it is needed for a debug 
session.

Thanks,
Bengt