RFR: 8343767: Enumerate StubGen blobs, stubs and entries and generate code from declarations [v4]

[Andrew Dinn]

> Implementation of JDK-8343767

Andrew Dinn has updated the pull request incrementally with one additional commit since the last revision:

  fix element sizes in s390 copy routines

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21957/files
  - new: https://git.openjdk.org/jdk/pull/21957/files/bfdfe015..0f8eb111

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21957&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21957&range=02-03

  Stats: 12 lines in 1 file changed: 0 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/21957.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21957/head:pull/21957

PR: https://git.openjdk.org/jdk/pull/21957