call AudioBackend::drop_device() when dropping a backend.

It is not clear that ::drop_device() is part of the same semantic operation as ::stop(), so
we call them separatey

1 files changed, 1 insertions, 0 deletions

diff --git a/libs/ardour/audioengine.cc b/libs/ardour/audioengine.cc
index d6a511fdad..0b01f97f7a 100644
--- a/libs/ardour/audioengine.cc
+++ b/libs/ardour/audioengine.cc
@@ -564,6 +564,7 @@ AudioEngine::drop_backend ()
 {
 	if (_backend) {
 		_backend->stop ();
+        _backend->drop_device();
 		_backend.reset ();
 	}
 }