RFR: Uncolorize addresses when using Generational ZGC

[Anton Rybochkin]

Because of color bits in lower positions, object alignment size heuristics does not work with generational ZGC. This PR implements address uncolorizing so alignment size and hence object size is calculated correctly

-------------

Commit messages:
 - Uncolorize ZGC addresses

Changes: https://git.openjdk.org/jol/pull/65/files
  Webrev: https://webrevs.openjdk.org/?repo=jol&pr=65&range=00
  Stats: 76 lines in 4 files changed: 73 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jol/pull/65.diff
  Fetch: git fetch https://git.openjdk.org/jol.git pull/65/head:pull/65

PR: https://git.openjdk.org/jol/pull/65