RFR: 8273152: Store base archive path in CDSFileMapHeaderBase

[Yumin Qi]

Store base archive path offset in CDSFileMapHeaderBase (which should be invariant in evolving versions) so we can read the base archive name reliably from dynamic archive even with variant header sizes over versions.

tests: tier1-4

Thanks
Yumin

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Commit messages:
 - 8273152: Store base archive path in CDSFileMapHeaderBase

Changes: https://git.openjdk.java.net/jdk/pull/5584/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5584&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273152
  Stats: 48 lines in 7 files changed: 27 ins; 4 del; 17 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5584.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5584/head:pull/5584

PR: https://git.openjdk.java.net/jdk/pull/5584