FindJNI: Unify path search, fix support for Java 9
Java 9 restructured the standard location of the AWT libraries due to the removal of the JRE/JDK separation. We should check all possible combinations of subdirectories to the Java root directories to ensure that the libraries will be found after an upgrade. Furthermore, a root directory would contain both, include and library paths, so the search should be unified to ease maintenance on the module.
findjni-paths2 jobs for