RFR: 8286444: javac errors after JDK-8251329 are not helpful enough to find root cause

[Christoph Langer]

After https://bugs.openjdk.java.net/browse/JDK-8251329, javac throws errors when the classpath
contains jar files with . or .. in its name. The error message, however, does not help to find
the culprit. This could be improved.

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Commit messages:
 - JDK-8286444

Changes: https://git.openjdk.java.net/jdk/pull/8616/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8616&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286444
  Stats: 8 lines in 2 files changed: 5 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8616.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8616/head:pull/8616

PR: https://git.openjdk.java.net/jdk/pull/8616