Get rid of ArrayList arithmetics in JavaClass.getAnnotationEntries()
Note that this changes return value of getAnnotationEntries() to be null instead of zero-length array by default.

This is based on the following:
- All annotation entries come from a "RuntimeVisibleAnnotations" attribute on a class file
- According to JVM specification, ch.4.7.16
"Each ClassFile, field_info, and method_info structure may contain at most one RuntimeVisibleAnnotations attribute"

Thus there is no need to create an array of attributes and enumerate all those, as there is either zero or one such attribute.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1624614 13f79535-47bb-0310-9956-ffa450edef68