Fix how we build the statsd protos.

This lets us include frameworks protos, and use the constants
and messages from them.

Change-Id: I609d6e524f780e6a5beea543a68561bede47813e
Test: make
diff --git a/cmds/statsd/Android.bp b/cmds/statsd/Android.bp
index 5fcb8a1..a5eae15 100644
--- a/cmds/statsd/Android.bp
+++ b/cmds/statsd/Android.bp
@@ -31,5 +31,11 @@
         type: "full",
         export_proto_headers: true,
     },
+
+    export_shared_lib_headers: [
+        "libplatformprotos",
+    ]
+
 }
 
+