AndroidManifest.xml: specify an android:service for the espeak service.

This is to try and address the "java.lang.SecurityException: Not allowed to
bind to service Intent" error when using the spiel screen reader.

android/AndroidManifest.xml

@@ -18,7 +18,8 @@
         <service
             android:name=".TtsService"
             android:label="@string/app_name"
-            android:exported="false" >
+            android:exported="false"
+            android:process=":texttospeech" >
             <intent-filter>
                 <action android:name="android.intent.action.TTS_SERVICE" />