Add METADATA to libunwind: MIT+Apache2=NOTICE am: 96a62d4598 am: 6860a68a20 am: 56a93418ed

Change-Id: If05efeac500b3ee217d29cc15b970cd44317aabd
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
+}