heads up: new lint warnings in Derby build

[Rick Hillegas]

As of my last checkin (revision 1480365), you will see the following 
lint warning in the Derby build:

    [javac] Note: Some input files use unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.
For a while, you may see a couple of these until we finish removing 
support for Java 5 and CDC (see DERBY-6213).

Thanks for your patience,
-Rick