Fix IndexOutOfBoundsException.

Backtrace:

E/AndroidRuntime(23398): Caused by: java.lang.IndexOutOfBoundsException:
Invalid index 0, size is 0
E/AndroidRuntime(23398):        at
java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
E/AndroidRuntime(23398):        at
java.util.ArrayList.get(ArrayList.java:308)
E/AndroidRuntime(23398):        at
com.cyanogenmod.eleven.loaders.SortedCursor.getExtraData(SortedCursor.java:120)
E/AndroidRuntime(23398):        at
com.cyanogenmod.eleven.loaders.SongLoader.loadInBackground(SongLoader.java:114)
E/AndroidRuntime(23398):        at
com.cyanogenmod.eleven.loaders.SongLoader.loadInBackground(SongLoader.java:40)
E/AndroidRuntime(23398):        at
com.cyanogenmod.eleven.sectionadapter.SectionCreator.loadInBackground(SectionCreator.java:69)
E/AndroidRuntime(23398):        at
com.cyanogenmod.eleven.sectionadapter.SectionCreator.loadInBackground(SectionCreator.java:30)
E/AndroidRuntime(23398):        at
android.support.v4.content.AsyncTaskLoader.onLoadInBackground(AsyncTaskLoader.java:242)
E/AndroidRuntime(23398):        at
android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:51)
E/AndroidRuntime(23398):        at
android.support.v4.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:40)
E/AndroidRuntime(23398):        at
android.support.v4.content.ModernAsyncTask$2.call(ModernAsyncTask.java:123)
E/AndroidRuntime(23398):        at
java.util.concurrent.FutureTask.run(FutureTask.java:237)

Change-Id: Ief99bf8b761bcdbccbcaefed6f54aa57e0ba9fbb