:art: PortMidi: remove useless usleep

diff --git a/plug b/plug
index c812ccc55b6c51aa91b5d5610e82925cdb084d8b..4591ae76c605507f2097b2ee9e53748e41b91ac1 160000 (submodule)
--- a/plug
+++ b/plug
@@ -1 +1 @@
-Subproject commit c812ccc55b6c51aa91b5d5610e82925cdb084d8b
+Subproject commit 4591ae76c605507f2097b2ee9e53748e41b91ac1