Suppress deprecation warning for DBCursor.OptionalFinalizer#finalize

Java 9 has deprecated Object#finalize, which generates a warning for
any class overriding it.  This commit suppresses that warning.  When
the finalize method is eventually removed, this method will become a
no-op as it will never be called, but there's no reason we need to
warn on it.

Author: jyemin

driver-legacy/src/main/com/mongodb/DBCursor.java

@@ -1008,6 +1008,7 @@ private void setServerCursor(@Nullable final ServerCursor serverCursor) {
         }
 
         @Override
+        @SuppressWarnings("deprecation")
         protected void finalize() {
             if (serverCursor != null) {
                 mongo.addOrphanedCursor(serverCursor, namespace);