#196556: NPE from ClassReader.findMethod inside NbBundleProcessor

http://netbeans.org/bugzilla/show_bug.cgi?id=196556
http://hg.netbeans.org/main/rev/72fc5f310d23

Under fairly specialized conditions involving a subset of files in a module having been previously compiled, and them using nested inner classes, it is possible for the 
processor for @Messages to trigger a NPE in javac.

Impact: annoying since it can cause confusing build failures during incremental builds. Workaround is do a clean build of the affected module.

Risk of fix: low since it just catches the NPE and tries something else (falling back to a simplified version of the code used prior to the fix of #196104), so unlikely 
to be any worse; some risk remains that the fix is not always effective if some other problem arises in javac. Tested on known cases for reproducing original bug. Not 
verified by QE.