RFR: JDK-8299994: java/security/Policy/Root/Root.java fails when home directory is read-only [v4]

[Bill Huang]

> Root.java is changed to a manual test because it requires test to be run with the root user privilege, and it requires to modify the user policy file in the home director.

Bill Huang has updated the pull request incrementally with one additional commit since the last revision:

  Check non-windows platform before retrieving user id.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12354/files
  - new: https://git.openjdk.org/jdk/pull/12354/files/3b736036..49848a01

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12354&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12354&range=02-03

  Stats: 14 lines in 1 file changed: 3 ins; 0 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/12354.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12354/head:pull/12354

PR: https://git.openjdk.org/jdk/pull/12354