Niklāvs Koļesņikovs authored Jun 24, 2021 and Wim Taymans committed Jun 24, 2021

Some distributions set --auto_features=enabled which messes with the
internal logic of the build system when features are used for other
purposes than pure dependency control. The only solution is to either
avoid the value auto or change the type of the option to non-feature.

This commit does the later by replacing -Dmedia-session, -Dwireplumber
and -Dsession-manager with the new -Dsession-managers array and
-Ddefault-session-manager combo options.

Fixes #1333
Fixes #1336