bug in rebuild_zebra verbose logging - found another print I didn't want to see all...

bug in rebuild_zebra verbose logging - found another print I didn't want to see all the time

Add the phrase 'if ( $verbose_logging )' to the two print statements
concerning the skipping of biblio or authority records.

I recently had to split biblio and authority index updating in my cron
script ( had some really big records so had to add the -x switch which
should only be used on biblios accourding to the help ).  So I noticed
that rebuild_zebra.pl printed messages that it was skipping biblios or
authorities.

This patch is to conditionalize those prints based on the verbose
logging switch.

Signed-off-by: Henri-Damien LAURENT <henridamien.laurent@biblibre.com>