libmediaplayerservice: fix warnings, make warnings errors, use clang

Change-Id: I1b2f6b65c5abbc366068a60b8909104f31b94228
diff --git a/media/libmediaplayerservice/MetadataRetrieverClient.h b/media/libmediaplayerservice/MetadataRetrieverClient.h
index ce52b91..e71a29e 100644
--- a/media/libmediaplayerservice/MetadataRetrieverClient.h
+++ b/media/libmediaplayerservice/MetadataRetrieverClient.h
@@ -54,7 +54,7 @@
     virtual sp<IMemory>             extractAlbumArt();
     virtual const char*             extractMetadata(int keyCode);
 
-    virtual status_t                dump(int fd, const Vector<String16>& args) const;
+    virtual status_t                dump(int fd, const Vector<String16>& args);
 
 private:
     friend class MediaPlayerService;