fix equality comparison between border, padding and background (see FOP-2307 comments)

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1612817 13f79535-47bb-0310-9956-ffa450edef68
FOP-2307: Weird border color inheritance (hashCode collisions); change suggested by Alexios Giotis.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1612821 13f79535-47bb-0310-9956-ffa450edef68