Re: AIX support

Hi Alvaro,
Thank you for taking your time to look into the details.

I’ve submitted the latest changes to the master branch, which are now available in the annotations section here:
https://commitfest.postgresql.org/patch/6050/
I kindly request you to review this updated patch and share your valuable feedback.

Regarding your observation about the inclusion of mkldexport.sh and its usage in the makefiles — as previously
discussed, this is a necessary workaround due to current limitations on AIX. To build shared libraries, we need to
extract symbols using this script. The relevant details are as follows:
Script Location: src/backend/port/aix/mkldexport.sh
Purpose: Implements AIX-specific changes for shared library creation using export files.
Background: Based on discussions with the internal linker team, this method is currently required to extract symbols and build shared libraries.
Reference Practices: This approach is consistent with methods used in other open-source projects such as Python and OpenBLAS:
Python
https://github.com/python/cpython/blob/main/Modules/ld_so_aix.in
OpenBLAS
https://github.com/OpenMathLib/OpenBLAS/commit/892f8ff3e55e24fda9af3f6364319cce3f60116b#diff-4011a114c75fe804332139868806cbe23f275963e4e6afa9b57e51b2b98

As for Meson builds, we did explore them earlier but encountered some issues. Here are some issues/fixes we submitted to the meson community
https://github.com/mesonbuild/meson/issues/14334
For now, we would like to focus initially on the regular gmake build since our buildfarms predominantly use it. That said, we do plan to submit Meson-related changes as a separate patch in the future.

Looking forward to your feedback.

-Sriram