This allows building wireplumber as part of the pipewire build
and running it in the uninstalled environment instead of media-session.
Building each session manager is individually contolled by the options:
-Dmedia-session=auto/enabled/disabled
-Dwireplumber=auto/enabled/disabled
And controlling which one is used in pipewire.conf is done with:
-Dsession-manager=media-session/wireplumber
Wireplumber's source tree must be in subprojects/wireplumber/
If this is missing, the .wrap file ensures that the latest git
master is downloaded while meson configures the build.
This git tree will not be automatically updated later, you need
to ensure that it is up-to-date on your own.
