RFR: 8268857: Merge VM_PrintJNI and VM_PrintThreads and remove the unused field 'is_deadlock' of DeadlockCycle [v4]

[Denghui Dong]

> Hi,
> 
> Could I have a review of this change that merges three vm operations(VM_PrintThreads, VM_PrintJNI, VM_FindDeadlocks) in thread_dump and signal_thread_entry.
> 
> `jstack` is a very common command, even in the production environment.
> 
> In addition to reduce the cost of entering safepoint, I think this patch also could ensure the consistency of the results of VM_PrintThreads and VM_FindDeadlocks.

Denghui Dong has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  update

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4504/files
  - new: https://git.openjdk.java.net/jdk/pull/4504/files/42faa20b..01a0308d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4504&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4504&range=02-03

  Stats: 67 lines in 7 files changed: 12 ins; 42 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4504.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4504/head:pull/4504

PR: https://git.openjdk.java.net/jdk/pull/4504