Fix NPE in TextToSpeech with setLanguage(null)

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

Change-Id: I8046e94959404bd63b0a90bcc2dbf4018f77c110
diff --git a/core/java/android/speech/tts/TextToSpeech.java b/core/java/android/speech/tts/TextToSpeech.java
index 26c167e..841257f 100755
--- a/core/java/android/speech/tts/TextToSpeech.java
+++ b/core/java/android/speech/tts/TextToSpeech.java
@@ -1065,6 +1065,9 @@
             if (!mStarted) {
                 return result;
             }
+            if (loc == null) {
+                return result;
+            }
             try {
                 String language = loc.getISO3Language();
                 String country = loc.getISO3Country();