RFR: 8201800: Add support for adjusting heap addresses in a TLAB

[Per Liden]

This patch adds support for iterating over and adjusting heap addresses 
contained in TLABs. A user of this would be ZGC, which sometimes wants 
to adjust the color of those pointers. This patch adds a new function, 
ThreadLocalAllocBuffer::addresses_do(), which takes a function/functor 
and applies that to all addresses in the TLAB.

Bug: https://bugs.openjdk.java.net/browse/JDK-8201800
Webrev: http://cr.openjdk.java.net/~pliden/8201800/webrev.0

/Per