RFR: Add support for AIX in build process [v2]

[Suchismith Roy]

> Summary of the issues: 
> 
> 1. There is no support for compiling AIX dynamic .a library and the tool was compiling .so files instead. 
> 2. There is no logic to support libclang.a. 
> 3.  There is no support to load shared member of .a dynamic libraries of AIX. 
> 
> JBS Issue: [CODETOOLS-7904116](https://bugs.openjdk.org/browse/CODETOOLS-7904116)

Suchismith Roy has updated the pull request incrementally with one additional commit since the last revision:

  Restore gradlew executable

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

Changes:
  - all: https://git.openjdk.org/jextract/pull/297/files
  - new: https://git.openjdk.org/jextract/pull/297/files/847e9bfe..a94e0a32

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jextract&pr=297&range=01
 - incr: https://webrevs.openjdk.org/?repo=jextract&pr=297&range=00-01

  Stats: 252 lines in 1 file changed: 252 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jextract/pull/297.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/297/head:pull/297

PR: https://git.openjdk.org/jextract/pull/297