RFR: 8256306: ObjectMonitor::_contentions field should not be 'jint' [v2]

[Coleen Phillimore]

> I changed the _contentions and _waiters fields from jint to int and ran tests tier1-3.  Tested tier1 with linux, mac, windows platforms. Also changed the _previous_owner_tid to unintptr_t from jlong, since that's what the cast did.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  Fix INT32_MIN and cache padding.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3980/files
  - new: https://git.openjdk.java.net/jdk/pull/3980/files/7c287908..07138653

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3980&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3980&range=00-01

  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3980.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3980/head:pull/3980

PR: https://git.openjdk.java.net/jdk/pull/3980