RFR: 8275063: Implementation of Foreign Function & Memory API (Second incubator) [v15]

[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 incrementally with one additional commit since the last revision:

  Simplify ArenaAllocator impl.
  The arena should respect its boundaries and never allocate more memory than its size specifies.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5907/files
  - new: https://git.openjdk.java.net/jdk/pull/5907/files/c219ae12..7f847271

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5907&range=14
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5907&range=13-14

  Stats: 40 lines in 1 file changed: 8 ins; 15 del; 17 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