RFR: 8314949: linux PPC64 Big Endian: Implementation of Foreign Function & Memory API [v2]

[Martin Doerr]

> I've found a way to solve the remaining FFI problem on linux PPC64 Big Endian. Large structs (>8 Bytes) which are passed in registers or on stack require shifting the Bytes in the last slot if the size is not a multiple of 8. This PR adds the required functionality to the Java code.
> 
> Please review and provide feedback. There may be better ways to implement it. I just found one which works and makes the tests pass:
> 
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR   
>    jtreg:test/jdk/java/foreign                          88    88     0     0   
> 
> 
> Note: This PR should be considered as preparation work for AIX which also uses ABIv1.

Martin Doerr has updated the pull request incrementally with one additional commit since the last revision:

  Implement ABI version selection by virtual method instead of instanceof check.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15417/files
  - new: https://git.openjdk.org/jdk/pull/15417/files/5d7b0e1d..50144b14

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15417&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15417&range=00-01

  Stats: 16 lines in 3 files changed: 13 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/15417.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15417/head:pull/15417

PR: https://git.openjdk.org/jdk/pull/15417