RFR (S): JDK-8077873: G1: Remove G1SATBPrintStubs

[Bengt Rutisson]

Hi everyone,

Sending this to hotspot-dev since it is a GC change but it touches 
compiler code in macroAssembler_sparc.cpp.

https://bugs.openjdk.java.net/browse/JDK-8077873
http://cr.openjdk.java.net/~brutisso/8077873/webrev.00/

The develop flag G1SATBPrintStubs prints out the generated assembly for 
the SATB stubs. This is has been around since G1 was integrated in the 
the hotspot repo. But it was only ever implemented for Sparc and it 
looks much like debugging code that has just been left in the code base.

I have not heard of anyone using this flag lately so rather than 
generalizing it to all platforms I propose that we remove it. If we need 
to debug the SATB write barrier generation we can easily add back 
similar logging.

Thanks,
Bengt