Build: test: f46-issues-2.1

[wenningerk]

Build: test: assure aggregate returns are allowed with cmocka files
disable flag both for compile and linking because of LTO

use pyproject build macros where available

[nrwahl2]

disable flag both for compile and linking because of LTO

LTO == link-time optimization, or something else? How is it relevant here?

What error did we observe, what code triggered it, and is it only on certain platforms or software versions?

[wenningerk]

disable flag both for compile and linking because of LTO

LTO == link-time optimization, or something else? How is it relevant here?

What error did we observe, what code triggered it, and is it only on certain platforms or software versions?

yep exactly - link-time optimization - which is the reason why it falls over that warning either at compile time or link time as with LTO enabled the actual compilation is done just then. So we need the warning to be allowed with link & compile-time flags.
With default flags of current rawhide (f46) the aggregate-returns (used by cmocka) warning is enabled (didn't check since when it actually exists) and as we fail on warnings build was failing. We've merged that already on main and as I was updating a 2.1 PR I stumbled over the issue there as well so I cherry-picked that commit.
This should actually be uncritical regarding modification of the default flags as the code built with the warning disabled doesn't go into the productive parts of pacemaker.
If you think it is worth it - make a suggestion for a short description that explains the point above that I can use to amend the commit comment.
Not sure if it is worth it trying to address the issue in a way that aggregate returns aren't used in the first place.
For now it at least makes CI happy.

[wenningerk]

added the python build-macro stuff that went into main and is on the 3.0 PR for f46-issues.
additional cleanup as a result of feedback for what I had done for Fedora builds.
I could squash the 2 commits dealing with python building. But as the 1st one is already merged into main (new PR for the cleanup) we might as well keep them separate.