Release bitflags 1.2.1 rust crate

Fetched with get.rust.pkg and Android.bp generated with
cargo2android.py.

Change-Id: I302ab0359d3688dbc83e9d1eb7a26364e3bae726
(cherry picked from commit 8729341d8fc2cba6809c171e09017262e6acdb60)
diff --git a/METADATA b/METADATA
new file mode 100644
index 0000000..ee6a075
--- /dev/null
+++ b/METADATA
@@ -0,0 +1,16 @@
+name: "bitflags"
+description:
+    "A Rust macro to generate structures which behave like a set of bitflags."
+
+third_party {
+  url {
+    type: HOMEPAGE
+    value: "https://crates.io/crates/bitflags"
+  }
+  url {
+    type: GIT
+    value: "https://github.com/bitflags/bitflags"
+  }
+  version: "1.2.1"
+  last_upgrade_date { year: 2019 month: 12 day: 12 }
+}