optimize echo limiter

diff --git a/mediastreamer2 b/mediastreamer2
index d48296689764e1f5f27f16c881ee4c5dcb8445dd..c5959fa4520005013cd14d2f773116f24f2eb7b7 160000 (submodule)
--- a/mediastreamer2
+++ b/mediastreamer2
@@ -1 +1 @@
-Subproject commit d48296689764e1f5f27f16c881ee4c5dcb8445dd
+Subproject commit c5959fa4520005013cd14d2f773116f24f2eb7b7