AopAutoConfiguration ought to be conditional on aspectjweaver

[dsyer]

Most (all) of what happens in AopAutoConfiguration is to @EnableAspectJAutoProxy. Proxies cannot be created unless the aspectjweaver is on the classpath. If the user wants to use AspectJ natively they wouldn't include the weaver, so logically it makes sense to back off if the weaver isn't present.

[snicoll]

MetricRepositoryAutoConfigurationTests fails now with this change:

java.lang.ArrayStoreException: sun.reflect.annotation.TypeNotPresentExceptionProxy

	at sun.reflect.annotation.AnnotationParser.parseClassArray(AnnotationParser.java:724)
	at sun.reflect.annotation.AnnotationParser.parseArray(AnnotationParser.java:531)
	at sun.reflect.annotation.AnnotationParser.parseMemberValue(AnnotationParser.java:355)
	at sun.reflect.annotation.AnnotationParser.parseAnnotation2(AnnotationParser.java:286)
	at sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:120)
	at sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:72)
	at java.lang.Class.createAnnotationData(Class.java:3521)
	at java.lang.Class.annotationData(Class.java:3510)
	at java.lang.Class.getAnnotations(Class.java:3446)
	at org.springframework.core.type.StandardAnnotationMetadata.<init>(StandardAnnotationMetadata.java:69)
	at org.springframework.beans.factory.annotation.AnnotatedGenericBeanDefinition.<init>(AnnotatedGenericBeanDefinition.java:58)```