RFR: 7903890: jcstress: Rewrite/amend Singleton and Lazy primitives samples [v2]

[Aleksey Shipilev]

> It is obvious we do not have a good narrative around these, so let's add some.

Aleksey Shipilev has updated the pull request incrementally with two additional commits since the last revision:

 - Missing headers
 - Amendments: performance tests

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

Changes:
  - all: https://git.openjdk.org/jcstress/pull/155/files
  - new: https://git.openjdk.org/jcstress/pull/155/files/9ff92719..07503013

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jcstress&pr=155&range=01
 - incr: https://webrevs.openjdk.org/?repo=jcstress&pr=155&range=00-01

  Stats: 623 lines in 13 files changed: 611 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jcstress/pull/155.diff
  Fetch: git fetch https://git.openjdk.org/jcstress.git pull/155/head:pull/155

PR: https://git.openjdk.org/jcstress/pull/155