RFR: JDK-8315706: com/sun/tools/attach/warnings/DynamicLoadWarningTest.java real fix for failure on AIX

[JoKern65]

After push of [JDK-8307478](https://bugs.openjdk.org/browse/JDK-8307478) , the following test started to fail on AIX :
com/sun/tools/attach/warnings/DynamicLoadWarningTest.java;
The problem was described in [JDK-8309549](https://bugs.openjdk.org/browse/JDK-8309549) with a first try of a fix.
A second fix via [JDK-8310191](https://bugs.openjdk.org/browse/JDK-8310191) was necessary.
Both fixes just disable the specific subtest on AIX, without correction of the root cause.
The root cause is, that dlopen() on AIX returns different handles every time, even if you load a library twice. There is no official AIX API available to get this information on a different way.
My proposal is, to use the stat64x API with the fields st_device and st_inode. After a dlopen() the stat64x() API is called additionally to get this information which is then stored parallel to the library handle in the jvmtiAgent. For AIX we then can compare these values instead of the library handle and get the same functionality as on linux.

-------------

Commit messages:
 - JDK-8315706

Changes: https://git.openjdk.org/jdk/pull/15583/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15583&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315706
  Stats: 121 lines in 5 files changed: 118 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15583.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15583/head:pull/15583

PR: https://git.openjdk.org/jdk/pull/15583