RFR(xs): 8152120: TLAB compute_size() should not allow any size larger than max_size

[sangheon]

Hi all,

Could I have a couple of reviews for this change to limit new TLAB size?

ThreadLocalAllocBuffer::compute_size() usually returns a value of 
'desired_size() + aligned object size'.
When ThreadLocalAllocBuffer::desired_size() reaches to the TLAB max 
size, we don't limit this value to be less than or equal to TLAB max size.

This change is proposing to limit to ThreadLocalAllocBuffer::max_size().

CR: https://bugs.openjdk.java.net/browse/JDK-8152120
Webrev: http://cr.openjdk.java.net/~sangheki/8152120/webrev.00
Testing: JPRT

Thanks,
Sangheon