Handle null cursor

If for some reason the SmsProvider returns a null cursor when we try
and load the SIM messages, show the "no sim messages" UI rather than
leaving the UI in a constant loading (animated loading cursor) state.
This is part three of three fixes for BC-triaged bug 2205782.

Change-Id: Ie3dceea621f8c2aa0a2c98f79278c120df3c37e7
diff --git a/src/com/android/mms/ui/ManageSimMessages.java b/src/com/android/mms/ui/ManageSimMessages.java
index 3d8059e..077e2d6 100644
--- a/src/com/android/mms/ui/ManageSimMessages.java
+++ b/src/com/android/mms/ui/ManageSimMessages.java
@@ -140,6 +140,9 @@
                 }
                 startManagingCursor(mCursor);
                 registerSimChangeObserver();
+            } else {
+                // Let user know the SIM is empty
+                updateState(SHOW_EMPTY);
             }
         }
     }