Add METADATA to poplar: Apache2+BSD=NOTICE

Bug: 68860345
Bug: 69058154
Bug: 151953481

Test: no code changes
Change-Id: I6a68887ce855a7c3a9815892ccc034ff1f185f05
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
+}