Fluidsynth's systemd unit currently has a hard dependency on the
pulseaudio systemd service. Since fluidsynth can use other sound
services (e.g., pipewire-pulse), this should be configurable. This
commit adds the relevant option.
PR #2238
Before, loading a module would be guarded by an optional platform
condition. This made it possible to avoid loading and evaluating a
module if it did not support the host platform.
Unfortunately, this made it impossible to share a single configuration
between GNU/Linux and Darwin hosts, which some wish to do.
This removes the conditional load and instead inserts host platform
assertions in the modules that are platform specific.
Fixes#1906
