JDK 9 RFR of 8175335: Improve handling of module types in javax.lang.model.util.Types

[joe darcy]

Hello,

Please review the small spec and implementation changes for

     8175335: Improve handling of module types in 
javax.lang.model.util.Types
     http://cr.openjdk.java.net/~darcy/8175335.0/

which treats pseudo-types for modules similarly to the pseudo-types for 
packages.

Thanks,

-Joe