RFR: 8254274: Development to add 'lint' warning for @ValueBased classes [v2]

[Srikanth Adayapalam]

> New javac lint mode (-Xlint:synchronize) to warn about client side as well JDK internal attempts to synchronize on instances of value based classes

Srikanth Adayapalam has updated the pull request incrementally with one additional commit since the last revision:

  8254274: Incorporate review comments

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Changes:
  - all: https://git.openjdk.java.net/valhalla/pull/237/files
  - new: https://git.openjdk.java.net/valhalla/pull/237/files/8c962dc7..1a660823

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=valhalla&pr=237&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=valhalla&pr=237&range=00-01

  Stats: 339 lines in 18 files changed: 70 ins; 251 del; 18 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/237.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/237/head:pull/237

PR: https://git.openjdk.java.net/valhalla/pull/237