[java/cs] Unit tests now run correctly with -dce no
- fixed co/contra-variance overrides
- fixed late Codegen.get_underlying_type application
- java Int64-related errors (precision loss)


git-svn-id: http://haxe.googlecode.com/svn/trunk@6403 f16182fa-f095-11de-8f43-4547254af6c6