[PATCH] Small performance improvements by adding static declarations

I was profiling an application running FOP 1.0 and found a few hotspots. Some of them have been already fixed in trunk ( e.g. FOP-1888 ).

The ones requiring minimal changes are contained in this patch. It adds the 'static' declaration for loggers and removes 2 heavily used trace logging messages. I avoided to include bigger changes (mainly in FObj which would benefit by using a LinkedList instead of the siblings array) as bigger patches seem to be difficult to process ( #46962 )