Fix goto/label in macros invoked from another module.

[dcjones]

This sort of thing previously incorrectly threw an error

module A
    macro some_macro()
        quote
            function $(esc(:foo))
                @label a
                @goto a
            end
        end
    end
end

A.@some_macro

It would try to rewrite @label a with @label A.a, this commit adds an special case to avoid that.