RFR: 8286191: misc tests fail due to JDK-8285987 [v3]

[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 incrementally with one additional commit since the last revision:

  restore year in ExternalEditorTest, remove test exclusion

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8556/files
  - new: https://git.openjdk.java.net/jdk/pull/8556/files/96f508df..2337301c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8556&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8556&range=01-02

  Stats: 2 lines in 2 files changed: 0 ins; 1 del; 1 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