isCglibProxy* methods in AopUtils are useful in lower-level modules,
i.e. those that cannot depend on .aop. Therefore copied these methods
to ClassUtils; deprecated the existing ones in AopUtils and now
delegating to the new location; switched all usage of
AopUtils#isCglibProxy* within the framework to use
ClassUtils#isCglibProxy* instead.
git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@4679 50f2f4bb-b051-0410-bef5-90022cba6387