RFR: 8315362: NMT: summary diff reports threads count incorrectly [v7]

[Evgeny Ignatenko]

> 8315362: NMT: summary diff reports threads count incorrectly

Evgeny Ignatenko has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains eight additional commits since the last revision:

 - Merge branch 'openjdk:master' into pr/8315362
 - Move thread count to MemBaseline
 - Not check exact amount of added threads
 - Remove bootclasspath from test
 - Change thread_count var type to size_t
 - Review comments
 - Resolve conflicts
 - 8315362: NMT: summary diff reports threads count incorrectly

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15490/files
  - new: https://git.openjdk.org/jdk/pull/15490/files/95343d73..9aed8dfd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15490&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15490&range=05-06

  Stats: 104068 lines in 2978 files changed: 43379 ins; 20825 del; 39864 mod
  Patch: https://git.openjdk.org/jdk/pull/15490.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15490/head:pull/15490

PR: https://git.openjdk.org/jdk/pull/15490