8156143: Module.getResourceAsStream throws unspecified SecurityException with module in custom Layer

[Alan Bateman]

This is minor mismatch between javadoc + implementation when 
getResourceAsStream is called on a module in a custom Layer and access 
is denied by the security manager. It's a one line fix, this is mostly 
just a new test:
   http://cr.openjdk.java.net/~alanb/8156143/webrev/
Thanks,
-Alan