Add libremain build file.

Bug: 140201589
Test: m libremain
Change-Id: I20b1993208da9f0be8ae72e82053842631a46f96
diff --git a/Android.bp b/Android.bp
new file mode 100644
index 0000000..300b29c
--- /dev/null
+++ b/Android.bp
@@ -0,0 +1,12 @@
+rust_proc_macro {
+    name: "libremain",
+    crate_name: "remain",
+    srcs: ["src/lib.rs",],
+    edition: "2018",
+    host_supported: true,
+    rlibs: [
+        "libquote",
+        "libsyn",
+        "libproc_macro2",
+    ],
+}