[packages/meson] - install rpm macros for meson prep/build/install, rel 2

[Jan Palus]

On 03.02.2025 10:10, baggins wrote:
> commit 181b4a43bc70a3d8032d2d79434a37df8ffcd867
> Author: Jan Rękorajski <baggins at pld-linux.org>
> Date:   Mon Feb 3 09:59:20 2025 +0100
> 
>     - install rpm macros for meson prep/build/install, rel 2

Mind that these macros use %{_smp_build_ncpus} which requires
rpm.org >= 4.15 and is unconstrained by anything in our macros hence you
got "-j 56" instead of expected "-j 28" in glycin build.

Also --default-library=both is lost which otherwise defaults to
"shared".