RFR: 8267583: jmod fails on symlink to class file

[Athijegannathan Sundararajan]

FileVisitOption.FOLLOW_LINKS used. Test extended for file symlinks case.

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Commit messages:
 - 8267583: jmod fails on symlink to class file

Changes: https://git.openjdk.java.net/jdk/pull/4202/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4202&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267583
  Stats: 41 lines in 2 files changed: 39 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4202.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4202/head:pull/4202

PR: https://git.openjdk.java.net/jdk/pull/4202