Update db only if ContentValues obj being inserted is not empty.

This hasn't been reported on shamu yet but this should be fixed because
if the issue is seen it renders the device unusable (leads to a crash
loop).

Bug: 20701423
Change-Id: I42e8fc05b39976b0ec07c0eefcca91b60f6d3694
diff --git a/src/com/android/providers/telephony/TelephonyProvider.java b/src/com/android/providers/telephony/TelephonyProvider.java
index 1a8fa16..37cab24 100644
--- a/src/com/android/providers/telephony/TelephonyProvider.java
+++ b/src/com/android/providers/telephony/TelephonyProvider.java
@@ -811,8 +811,14 @@
                 mergedValues.putAll(newRow);
             }
 
-            db.update(table, mergedValues, "_id=" + oldRow.getInt(oldRow.getColumnIndex("_id")),
-                    null);
+            if (mergedValues.size() > 0) {
+                try {
+                    db.update(table, mergedValues, "_id=" + oldRow.getInt(oldRow.getColumnIndex("_id")),
+                            null);
+                } catch (Exception e) {
+                    loge("mergeFieldsAndUpdateDb: Exception on db update()");
+                }
+            }
         }
 
         static public Cursor selectConflictingRow(SQLiteDatabase db, String table,