RFR(s): 8197994: Move JavaThread::initialize_queues() logic to G1SATBCardTableLoggingModRefBS

[Per Liden]

We introduced BarrierSet::flush_deferred_barriers() so that we could 
move G1's SATB logic out from JavaThread and into the 
G1SATBCardTableLoggingModRefBS barrier set. We should do the same thing 
with JavaThread::initialize_queues().

The new function on BarrierSet is called on_thread_create(). After 
talking to Erik Ö, we also decided to rename 
BarrierSet::flush_deferred_barriers() to on_thread_destroy(), to better 
match the existing on_slowpath_allocation_exit() and the new 
on_thread_create().

Bug: https://bugs.openjdk.java.net/browse/JDK-8197994
Webrev: http://cr.openjdk.java.net/~pliden/8197994/webrev.0/
Testing: hs-tier1,hs-tier2

/Per