Export include dirs from libsonic

am: 44dc9781

Change-Id: Ic7fabcff9f58845157b95f21fedd34bce4a5090a

Android.bp

@@ -9,6 +9,6 @@ cc_library_shared {
         "-Wall",
         "-Werror",
     ],
-
-    cppflags: ["-std=c++98"],
+    export_include_dirs: ["."],
+    cpp_std: "c++98",
 }