RFR: 8273300: Check Mutex ranking during a safepoint [v2]

[Coleen Phillimore]

> This change checks lock ranking during a safepoint.  For some reason, safepoint checking was excluded, probably from the days where Safepoint_lock and Threads_lock were used.
> Because of checking during a safepoint, some locks had to get lower ranks.  The CR has the details of which locks these were.  The Service_lock complicates things because it's held during oops_do, which may take out other G1 locks.
> This was built and tested with Shenandoah.  Thanks to @zhengyu123 for the changes in Shenandoah.
> Tests run tier1-8.

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

  Fix Shenandoah mismerge

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5467/files
  - new: https://git.openjdk.java.net/jdk/pull/5467/files/13355972..dcb03c3a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5467&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5467&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5467.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5467/head:pull/5467

PR: https://git.openjdk.java.net/jdk/pull/5467