Compressing class files in the module library

[Alan Bateman]

I've updated the patch [1] for the compression support to also add an 
option to strip the debug attributes from classes when installing a 
module. This time the proposed option is -G and --strip-debug and it's 
an option on jmod install so it's on a per module basis (to allow for 
debugging of application modules that are installed into the same module 
library as modules that don't have debug attributes). For now the 
implementation uses pack200 so it's makes -G a bit more expensive than 
it should be. This is easily changed in the future if we have a general 
class reader/write in the platform.

-Alan.

[1] http://cr.openjdk.java.net/~alanb/ModuleLibraryCompression/webrev/