RFR: 8275063: Implementation of Foreign Function & Memory API (Second incubator) [v26]

[Maurizio Cimadamore]

> This PR contains the API and implementation changes for JEP-419 [1]. A more detailed description of such changes, to avoid repetitions during the review process, is included as a separate comment.
> 
> [1] - https://openjdk.java.net/jeps/419

Maurizio Cimadamore has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 35 commits:

 - Merge branch 'master' into JEP-419
 - Fix javadoc issues found in CSR review
 - Adopt blessed modofier order
 - Merge branch 'master' into JEP-419
 - Revert removal of upcall MH customization
   (This change caused spurious VM crashes, so reverting to baseline)
 - Further tweak upcall safety considerations
 - Clarify safety considerations for upcalls
 - Rename MemorySegment::ofAddressNative to MemorySegment::ofAddress
   (which is consistent with other restricted factories in VaList and NativeSymbol)
 - Streamline javadoc for package-info
 - * Add two new CLinker static methods to compute upcall/downcall method types
   * Clarify section on CLinker downcall type
   * Add section on CLinker safety guarantees
 - ... and 25 more: https://git.openjdk.java.net/jdk/compare/d427c79d...29cc6c60

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Changes: https://git.openjdk.java.net/jdk/pull/5907/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5907&range=25
  Stats: 14700 lines in 193 files changed: 6958 ins; 5126 del; 2616 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5907.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5907/head:pull/5907

PR: https://git.openjdk.java.net/jdk/pull/5907