[MPDF-48] make PDF plugin run reports when used with Maven 3 
Change signature of generateMavenReport in preparation of using MavenReportExecution.
Remove catch of LinkageError, can't get the ClassRealm through MavenReportExection

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1479146 13f79535-47bb-0310-9956-ffa450edef68