Add METADATA to libsrtp2: BSD+MIT=NOTICE am: 91e048d818

Change-Id: I92f8fa816ba5d4f3912cf77a4ea223a11bf1a261
diff --git a/METADATA b/METADATA
new file mode 100644
index 0000000..d97975c
--- /dev/null
+++ b/METADATA
@@ -0,0 +1,3 @@
+third_party {
+  license_type: NOTICE
+}