RFR: 7903044: Report `os.*` system properties in .jtr file [v2]

[Christian Stein]

> https://bugs.openjdk.java.net/browse/CODETOOLS-7903044

Christian Stein has updated the pull request incrementally with one additional commit since the last revision:

  Also emit test JDK's properties

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Changes:
  - all: https://git.openjdk.java.net/jtreg/pull/35/files
  - new: https://git.openjdk.java.net/jtreg/pull/35/files/5dd2adae..bd5a1ba9

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jtreg&pr=35&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jtreg&pr=35&range=00-01

  Stats: 7 lines in 2 files changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jtreg/pull/35.diff
  Fetch: git fetch https://git.openjdk.java.net/jtreg pull/35/head:pull/35

PR: https://git.openjdk.java.net/jtreg/pull/35