Re-filter findbugs exclusions, course grained.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1615842 13f79535-47bb-0310-9956-ffa450edef68
Fix or suppress 1-instance findbug warnings.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1616312 13f79535-47bb-0310-9956-ffa450edef68