RFR: 8304824: NMT should not use ThreadCritical [v5]

[Robert Toyonaga]

> ### Summary
> This PR just replaces `ThreadCritical` with a lock specific to NMT.  `ThreadCritical` is a big lock and is unnecessary for the purposes of NMT. I've implemented the new lock with a semaphore so that it can be used early before VM init.  There is also the possibility of adding assertions in places we expect NMT to have synchronization. I haven't added assertions yet in many places because some code paths such as the (NMT tests)  don't lock yet. I think it makes sense to close any gaps in locking in another PR in which I can also add more assertions. 
> 
> Testing:
> - hotspot_nmt
> - gtest:VirtualSpace
> - tier1

Robert Toyonaga has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - Merge master
 - replace tty in pd_release_memory while holding NMT lock.
 - Switch to using a Hotspot Mutex.
 - Comments. Hide assertion behind DEBUG. Replace MemoryFileTracker locker. make reentrant.
 - Replace ThreadCritical with a specific NMT lock

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Changes: https://git.openjdk.org/jdk/pull/20852/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20852&range=04
  Stats: 84 lines in 16 files changed: 34 ins; 21 del; 29 mod
  Patch: https://git.openjdk.org/jdk/pull/20852.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20852/head:pull/20852

PR: https://git.openjdk.org/jdk/pull/20852