prevent 'type already reffers to XXX' warnings on 'import package.*'

[David Holroyd]

as2api produces warnings like,

  org/foobar/MyClass.as: MyClass already refers to org.foobar.MyClass

I think this may be due to the appearence of an import like,

  import org.foobar.*;

within this file.

Since the warnings seem to be bogus, they should be avoided in this case.

[David Holroyd (dholroyd)]

a trivial change to api_loader.rb prevents these spurious messages