RFR: JDK-8314517: some tests fail in case ipv6 is disabled on the machine [v2]

[Matthias Baesken]

> Some jtreg tests fail with ipv6 disabled on the machine, this should be improved in the tests (e.g. by using IPSupport.hasIPv6() ).

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  adjust HostsFileOrderingTest

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15341/files
  - new: https://git.openjdk.org/jdk/pull/15341/files/2d5986e0..28205984

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15341&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15341&range=00-01

  Stats: 14 lines in 1 file changed: 3 ins; 2 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/15341.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15341/head:pull/15341

PR: https://git.openjdk.org/jdk/pull/15341