RFR: 8280404: Unexpected exception thrown when CEN file entry comment length is not valid

[Lance Andersen]

Hi all,

This PR addresses an issue where an unexpected exception is thrown when the CEN file entry comment length is not correct.

Mach5 tiers 1 - 3 run clean with this change.

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Commit messages:
 - Correct bug number in test
 - Validate comment if it exists when processing the CEN

Changes: https://git.openjdk.java.net/jdk/pull/7673/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7673&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280404
  Stats: 353 lines in 2 files changed: 352 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7673.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7673/head:pull/7673

PR: https://git.openjdk.java.net/jdk/pull/7673