context: add context.modules.allow-empty property

false by default, when true, no warning will be logged when the
context.modules in the config is empty. This can be useful when the
application wants to load all the modules itself.

doc/dox/config/pipewire.conf.5.md

@@ -253,6 +253,11 @@ Any property in the vm.overrides property object will override the property
 in the context.properties when PipeWire detects it is running in a VM. This
 is deprected, use the context.properties.rules instead.
 
+@PAR@ pipewire.conf  context.modules.allow-empty = false
+By default, a warning is logged when there are no context.modules loaded because this
+likely indicates there is a problem. Some applications might load the modules themselves
+and when they set this property to true, no warning will be logged.
+
 The context properties may also contain custom values. For example,
 the `context.modules` and `context.objects` sections can declare
 additional conditions that control whether a module or object is loaded

src/pipewire/context.c

@@ -357,7 +357,7 @@ struct pw_context *pw_context_new(struct pw_loop *main_loop,
 	pw_log_info("%p: parsed %d context.spa-libs items", this, res);
 	if ((res = pw_context_parse_conf_section(this, conf, "context.modules")) < 0)
 		goto error_free;
-	if (res > 0)
+	if (res > 0 || pw_properties_get_bool(properties, "context.modules.allow-empty", false))
 		pw_log_info("%p: parsed %d context.modules items", this, res);
 	else
 		pw_log_warn("%p: no modules loaded from context.modules", this);