[JEP424] Implement the Linker's downcall & upcall handler in JDKnext

[ChengJin01]

The changes aim to enable the Linker's downcall & upcall handler
to support primitives and struct by replacing DowncallLinker
& UpcallLinker with the equivalent implemented in OpenJ9.
In addition, the changes also include the code that handles
the default library loading on AIX.

Signed-off-by: Cheng Jin jincheng@ca.ibm.com

[ChengJin01]

The Java19 specific changes (downcall & upcall) in OpenJDK belong to the issue intended for the upcall work at #15068.
Note:

1. the PR also includes the code that ignores the alignment check for double/float to ensure it works for double related struct on AIX in Java 19 (never used in Java 17 & 18).
2. the PR depends on the java part in PR at [Part 1/JDK19] FFI Upcall: creating the upcall stub (java part) eclipse-openj9/openj9#15307 and the native code in Design and Implementation of Foreign Linker API: Upcall eclipse-openj9/openj9#15068.

Reviewer: @tajila
FYI: @DanHeidinga, @pshipton, @gacholio

[tajila]

jenkins test sanity plinux jdknext

[tajila]

@ChengJin01 some compilation failures here

[ChengJin01]

@ChengJin01 some compilation failures here

@tajila, the code changes depend on the latest downcall & upcall java code in OpenJ9 at eclipse-openj9/openj9#15307 as I mentioned at eclipse-openj9/openj9#15307 (comment); otherwise, the compilation will pick up the code in OpenJDK rather than OpenJ9 and end up with failing failure on Jenkins (e.g.https://openj9-jenkins.osuosl.org/job/Build_JDKnext_ppc64le_linux_Personal/48/consoleText)

[2022-07-18T12:45:46.609Z] /home/jenkins/workspace/Build_JDKnext_ppc64le_linux_Personal/src/java.base/share/classes/jdk/internal/foreign/abi/aarch64/CallArranger.java:161: error: method getBoundMethodHandle in class DowncallLinker cannot be applied to given types;
[2022-07-18T12:45:46.609Z]         MethodHandle handle = DowncallLinker.getBoundMethodHandle(mt, cDesc); 
<--- The failure was caused by the mismatch of arguments in getBoundMethodHandle() in OpenJDK. 
[2022-07-18T12:45:46.609Z]                                             ^
[2022-07-18T12:45:46.609Z]   required: no arguments
[2022-07-18T12:45:46.609Z]   found:    MethodType,FunctionDescriptor
[2022-07-18T12:45:46.609Z]   reason: actual and formal argument lists differ in length