Now that we use meson feature options for our dependencies, we can just
rely on '--auto-features=disabled' to do the same. One benefit of this
is that specific features can still be force-enabled by overriding it
with the appropriate '-Dfeature=enabled' flag.
The two remaining uses for skip-deps can simply rely on their default
logic that sets the value to 'no' when the dependency is disabled.
7f9a0d6d74