RFR: 8296754: AutoCreateSharedArchive in JDK 20 is not compatible with JDK 19 [v2]

[Matias Saavedra Silva]

> The -XX:+AutoCreateSharedArchive flag was implemented in JDK 19, however, this flag doesn't work across JDK 19 and 20.
> 
> Expected: JDK 20 should recreate the specified CDS archive
> Actual: JDK 20 cannot recognize the archive file and gives up
> 
> The new field from GenericCDSFileMapHeader is now in FileMapHeader. Verified with tier 1-4 tests.

Matias Saavedra Silva has updated the pull request incrementally with one additional commit since the last revision:

  Changed whitespace and comment

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11148/files
  - new: https://git.openjdk.org/jdk/pull/11148/files/732e331d..fd13805c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11148&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11148&range=00-01

  Stats: 13 lines in 2 files changed: 0 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/11148.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11148/head:pull/11148

PR: https://git.openjdk.org/jdk/pull/11148