RFR: 8309475: [aix] Test java/foreign/TestByteBuffer.java fails: a problem with msync

[Tyler Steele]

Solves the issue by searching `/proc/<pid>/map` for the map after an EINVAL. If the map is marked `MAP_PRIVATE` then EINVAL is ignored.

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Depends on: https://git.openjdk.org/jdk/pull/14904

Commit messages:
 - Remove dead code
 - Adds error validation for after call to force0 on AIX (msync)

Changes: https://git.openjdk.org/jdk/pull/14914/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14914&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309475
  Stats: 71 lines in 1 file changed: 71 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/14914.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14914/head:pull/14914

PR: https://git.openjdk.org/jdk/pull/14914