RFR: JDK-8151602: Make logging in refillLinearAllocBlockIfNeeded() available

[Bengt Rutisson]

Hi everyone,

Could I have a couple of reviews for this change?

http://cr.openjdk.java.net/~brutisso/8151602/webrev.00
https://bugs.openjdk.java.net/browse/JDK-8151602

In CompactibleFreeListSpace::refillLinearAllocBlockIfNeeded() we have 
this code:

   if (PrintMiscellaneous && Verbose) {
     if (blk->_word_size == 0) {
       warning("CompactibleFreeListSpace(prologue):: Linear allocation 
failure");
     }

It is a bit strange to guard a warning() this way. Verbose is a develop 
flag so the warning is never printed in product builds. This is also the 
only use of PrintMiscellaneous in the GC code.

Another strange thing about this logging is that is says "(prologue)" 
but refillLinearAllocBlockIfNeeded() is called from three places:

CompactibleFreeListSpace::gc_prologue()
CompactibleFreeListSpace::reset_after_compaction()
CompactibleFreeListSpace::sweep_completed()

Thanks,
Bengt