RFR: 8263460: DynamicArchiveRelocationTest.java fails in product VM

[Ioi Lam]

Please review this test bug. 

The handling of -XX:ArchiveRelocationMode=1 is different between fastdebug and product builds:

- fastdebug: (to improve test coverage) -- we always map at the default location, then unmap, and then map again at a random location.
- product: (for faster performance) -- don't attempt to map at the default location. Just map at random location

Therefore, the "unmap" messages are not available in product mode.

I added comments to explain what output is expected, and rearranged the regexp for better matching.

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Commit messages:
 - 8263460: DynamicArchiveRelocationTest.java fails in product VM

Changes: https://git.openjdk.java.net/jdk/pull/2947/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2947&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263460
  Stats: 46 lines in 1 file changed: 25 ins; 6 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2947.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2947/head:pull/2947

PR: https://git.openjdk.java.net/jdk/pull/2947