RFR: 8233725: ProcessTools.startProcess() has output issues when using an OutputAnalyzer at the same time [v2]

[Leonid Mesnik]

> ProcessTools.startProcess() creates process and read it's output error streams. So the any other using of corresponding Process.getInputStream() and Process.getErrorStream() doesn't get process streams.
> 
> This fix preserve process streams content and allow to read it after process completion. The another possible solution would be to throw exception when user tries to read already drained streams to fail tests earlier. However it complicates usage of ProcessTools.startProcess() methods.
> 
> The regression test has been provided with issue.

Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:

  JStackStressTest.java updated.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13560/files
  - new: https://git.openjdk.org/jdk/pull/13560/files/c1534166..38d82fa5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13560&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13560&range=00-01

  Stats: 3 lines in 1 file changed: 1 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13560.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13560/head:pull/13560

PR: https://git.openjdk.org/jdk/pull/13560