RFR: 8261090: Store old classfiles in static CDS archive [v4]

[Calvin Cheung]

> Please review this RFE for storing old classfiles with major version < 50 in static CDS archive.
> During static CDS dump time, old classes won't be verified/rewritten. They will be verified/rewritten during runtime.
> Therefore, the `_constMethod`, `_constants`, and `_cache` of old classes must be stored in the RW region of the archive for runtime rewriting. The `ConstantPool::remove_unshareable_info` will be skipped during dump time and the `ConstantPool::restore_unshareable_info` will be skipped during runtime for old classes.
> 
> Passed tiers 1,2,3,4 tests on mach5.

Calvin Cheung has updated the pull request incrementally with one additional commit since the last revision:

  comment from @yminqi, add comment to the is_old_class(), add the @bug tag to new tests

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3479/files
  - new: https://git.openjdk.java.net/jdk/pull/3479/files/a8ddecfe..ea81a6cc

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3479&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3479&range=02-03

  Stats: 8 lines in 7 files changed: 6 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3479.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3479/head:pull/3479

PR: https://git.openjdk.java.net/jdk/pull/3479