Varargs methods don't get annotated

In a codebase migrating to Java 5, some features might be allowed before others, for instance, varargs can be allowed before Java 5 annotations. Therefore, backport175 might need to work in an environment where varargs are being used in methods.

Currently, it fails to work because it doesn't use QDox info on whether a parameter is a vararg or not, building signatures based only on type information. AnnotationEnhancer should check for the varargs flag in order to build the VM signature for the method. A patch is attached.