Always delegate meter-point positioning to rt-thread

Previously set_state() -> set_meter_point() acquired the
process-lock to change meter-position, usually causing x-runs
when setting route-state.

This also fixes an issue introduced in fd414ec158. After
populating the processor list, force setting the meter-position
looks up the output streams of the processor before the meter.
However the processors are not configured. That will only happen
later from Session::post_engine_init().

---
#3 0x00007ff07b7d4102 in __GI___assert_fail at assert.c:101
#4 0x00007ff080d3224a in ARDOUR::PluginInsert::output_streams() const at ../libs/ardour/plugin_insert.cc:289
#5 0x00007ff080de8c30 in ARDOUR::Route::set_meter_point_unlocked() at ../libs/ardour/route.cc:4106
#6 0x00007ff080de8699 in ARDOUR::Route::set_meter_point(ARDOUR::MeterPoint, bool) at ../libs/ardour/route.cc:4037
#7 0x00007ff080ddfad3 in ARDOUR::Route::set_state(XMLNode const&, int) at ../libs/ardour/route.cc:269

1 files changed, 4 insertions, 4 deletions

diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index 7c653b6fe1..d420824219 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -2693,7 +2693,7 @@ Route::set_state (const XMLNode& node, int version)
 
 	MeterPoint mp;
 	if (node.get_property (X_("meter-point"), mp)) {
-		set_meter_point (mp, true);
+		set_meter_point (mp);
 		if (_meter) {
 			_meter->set_display_to_user (_meter_point == MeterCustom);
 		}
@@ -4022,13 +4022,13 @@ Route::emit_pending_signals ()
 }
 
 void
-Route::set_meter_point (MeterPoint p, bool force)
+Route::set_meter_point (MeterPoint p)
 {
-	if (_pending_meter_point == p && !force) {
+	if (_pending_meter_point == p) {
 		return;
 	}
 
-	if (force || !AudioEngine::instance()->running()) {
+	if (!AudioEngine::instance()->running()) {
 		bool meter_visibly_changed = false;
 		{
 			Glib::Threads::Mutex::Lock lx (AudioEngine::instance()->process_lock ());