RFR: ThreadSnapshot: redesign and cleanup [v2]

[Alex Menkov]

> ThreadSnapshot: redesign and cleanup

Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:

  ELIMINATED

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

Changes:
  - all: https://git.openjdk.org/loom/pull/220/files
  - new: https://git.openjdk.org/loom/pull/220/files/8699cd0e..5269e798

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=loom&pr=220&range=01
 - incr: https://webrevs.openjdk.org/?repo=loom&pr=220&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/loom/pull/220.diff
  Fetch: git fetch https://git.openjdk.org/loom.git pull/220/head:pull/220

PR: https://git.openjdk.org/loom/pull/220