RFR: 8254102: use ProcessHandle::pid instead of ManagementFactory::getRuntimeMXBean to get pid in tests [v2]

[Igor Ignatyev]

> Hi all,
> 
> could you please review this small cleanup which replaces
> `ManagementFactory.getRuntimeMXBean().getName().split("@")[0]` w/ `ProcessHandle.current().pid()` to get current
> process pid?  Thanks,
> -- Igor

Igor Ignatyev has updated the pull request incrementally with two additional commits since the last revision:

 - use Long.toString instead of String.valueOf
 - remove explicit coversion to String in Suicide.java

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/534/files
  - new: https://git.openjdk.java.net/jdk/pull/534/files/b6f4b94a..bc6e3515

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=534&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=534&range=00-01

  Stats: 8 lines in 6 files changed: 0 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/534.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/534/head:pull/534

PR: https://git.openjdk.java.net/jdk/pull/534