RFR: 8286191: misc tests fail due to JDK-8285987 [v4]

[Matthias Baesken]

> The isMusl method had to be handled in test/lib-test/jdk/test/lib/TestMutuallyExclusivePlatformPredicates.java .
> Additionally, the vm.musl predicate seem not to be available in the langtools tests.

Matthias Baesken has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:

 - Merge remote-tracking branch 'origin/master' into JDK-8286191
 - restore year in ExternalEditorTest, remove test exclusion
 - Merge remote-tracking branch 'origin/master' into JDK-8286191
 - remove from ProblemList
 - Merge remote-tracking branch 'origin/master' into JDK-8286191
 - JDK-8286191

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8556/files
  - new: https://git.openjdk.java.net/jdk/pull/8556/files/2337301c..4c9e5b7e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8556&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8556&range=02-03

  Stats: 104552 lines in 1272 files changed: 94955 ins; 4519 del; 5078 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8556.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8556/head:pull/8556

PR: https://git.openjdk.java.net/jdk/pull/8556