Prior to this commit spring-web's dependence on spring-aop was marked
optional, however spring-web's required dependence on spring-context
transitively forces a required dependence on spring-aop anyway.
This change marks spring-aop as a required dependency of spring-web,
which a) reflects the poms created by the 3.2 Gradle build and b) helps
solve dependency issues when using higher-level Spring projects such as
Spring Security.
Issue: SPR-9573
9187eeff27