RFR: 8202989: Add missing decorators in calls to to arraycopy_prologue/epilogue

[Per Liden]

Calls to BarrierSetAssambler::arraycopy_prologue/epilogue() are missing 
the IN_HEAP and IN_HEAP_ARRAY access decorators. This is sort of ok, 
since the context (we're doing an arraycopy) imply these. However, by 
not explicitly specifying them we loose the ability to do straight 
forward checks/asserts on expected/allowed decorators later on in the GC 
specific BarrierSetAssermbler backends. To avoid having the backends 
know about this implicit relationship I propose that we explicitly 
specify them at the call-sites.

Bug: https://bugs.openjdk.java.net/browse/JDK-8202989
Webrev: http://cr.openjdk.java.net/~pliden/8202989/webrev.0
Testing: hs-tier{1,2}

/Per