Add cargo2android.json.

Test: Ran cargo2android. Treehugger.
Change-Id: I88da7b8e11ed5b9c18f671c340b5dc54f6e40f23
diff --git a/Android.bp b/Android.bp
index 2477e28..429532b 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,8 +1,6 @@
-// This file is generated by cargo2android.py --run --device.
+// This file is generated by cargo2android.py --config cargo2android.json.
 // Do not modify this file as changes will be overridden on upgrade.
 
-
-
 package {
     default_applicable_licenses: [
         "external_rust_crates_tracing-attributes_license",
@@ -24,7 +22,6 @@
 
 rust_proc_macro {
     name: "libtracing_attributes",
-    // has rustc warnings
     crate_name: "tracing_attributes",
     cargo_env_compat: true,
     cargo_pkg_version: "0.1.23",
diff --git a/cargo2android.json b/cargo2android.json
new file mode 100644
index 0000000..fe43c3f
--- /dev/null
+++ b/cargo2android.json
@@ -0,0 +1,4 @@
+{
+  "run": true,
+  "device": true
+}