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

[Andrew Dinn]

Implementation of JDK-8343767

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Commit messages:
 - locate super lookup stubs in same blob for all arches
 - do verification under ifdef ASSERT
 - fix yet more problems with s390 stubs
 - better error notification
 - fix more problems with s390 stubs
 - Verify stubs are generated in correct blob
 - fix problems with s390 stub address getters
 - fix problems with s390 stub declaration
 - correct merge problems
 - add new file for s390
 - ... and 41 more: https://git.openjdk.org/jdk/compare/23597361...1c0766a6

Changes: https://git.openjdk.org/jdk/pull/21957/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21957&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343767
  Stats: 6934 lines in 57 files changed: 4061 ins; 1535 del; 1338 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