RFR: 8292082: Deprecate UseRTM* for removal

[Roman Kennke]

HotSpot supports RTM (restricted transactional memory) to be used for locking and deoptimization. RTM has since been disabled in Intel processors due to security vulnerabilities [0] and IBM removed support for it since its Power 10 line. RTM adds unnecessarily to complexity and maintenance burden.

I would like to propose to deprecate the relevant flags for removal, and actually remove the flags and all related code in a later release, unless somebody comes up with a good reason and performance comparison to show that it's worth keeping.

[0] https://en.wikipedia.org/wiki/Transactional_Synchronization_Extensions#History_and_bugs

Testing:
 - [x] runtime/CommandLine/VMDeprecatedOptions.java
 - [ ] tier1

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Commit messages:
 - 8292082: Deprecate UseRTM* for removal

Changes: https://git.openjdk.org/jdk/pull/9810/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9810&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292082
  Stats: 12 lines in 2 files changed: 12 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/9810.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9810/head:pull/9810

PR: https://git.openjdk.org/jdk/pull/9810