Fix NPE in TextToSpeech with setLanguage(null)

getLanguage() can return null, and pass it to setLanguage()
  in TextToSpeech.initTts()

Change-Id: I8046e94959404bd63b0a90bcc2dbf4018f77c110

core/java/android/speech/tts/TextToSpeech.java

@@ -1065,6 +1065,9 @@ public class TextToSpeech {
             if (!mStarted) {
                 return result;
             }
+            if (loc == null) {
+                return result;
+            }
             try {
                 String language = loc.getISO3Language();
                 String country = loc.getISO3Country();