API and makefiles for ZRTP support.

[linphone] / mediastreamer2

diff --git a/mediastreamer2 b/mediastreamer2
index d1ea30fb58954005d1ac3c2a71fbcfcb85d3bf40..9091250591e54e6533cea8ba8c203f6f4f47550d 160000 (submodule)
--- a/mediastreamer2
+++ b/mediastreamer2
@@ -1 +1 @@
-Subproject commit d1ea30fb58954005d1ac3c2a71fbcfcb85d3bf40
+Subproject commit 9091250591e54e6533cea8ba8c203f6f4f47550d