RFR: 8240903: Add a regression test for JDK-8240734

[Dongbo He]

This creates a regression test for JDK-8240734. This was once blocked 
by a time stamp issue which has been resolved by: [JDK-8276766 ](https://bugs.openjdk.java.net/browse/JDK-8276766)

We found the issue can always be produced with at least 64 modules.
Note that we need to add the --date jmod option to avoid the timestamp issue.

Testing:
Added test case fails before JDK-8240734, and passes after JDK-8240734.
Tested with tier2 on linux x86.

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Commit messages:
 - 8240903: Add a regression test for JDK-8240734

Changes: https://git.openjdk.java.net/jdk/pull/7948/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7948&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8240903
  Stats: 78 lines in 3 files changed: 75 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7948.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7948/head:pull/7948

PR: https://git.openjdk.java.net/jdk/pull/7948