Fix NPE for CTS.

The effect list can be empty and will return null
from native code. This fixes the CTS crash.

Bug: 18256010
Change-Id: Ifa552efc9de216993427115c001c7071c90403f1

media/java/android/media/audiofx/AudioEffect.java

@@ -483,6 +483,10 @@ public class AudioEffect {
      */
     public static boolean isEffectTypeAvailable(UUID type) {
         AudioEffect.Descriptor[] desc = AudioEffect.queryEffects();
+        if (desc == null) {
+            return false;
+        }
+
         for (int i = 0; i < desc.length; i++) {
             if (desc[i].type.equals(type)) {
                 return true;