Bug 9859: fix nsb_clean side effect

Bug 9859: fix nsb_clean side effect

Signed-off-by: Mathieu Saby <mathieu.saby@univ-rennes2.fr>
This sub was causing 2 bugs :
- tools/exports.pl --clean was removing Â
- authority search plugin used in cataloging was removing  in suggested authorities displayed dynamicly (using ajax)
After applying the patch,
- NSB/NSE are still removed by nsb_clean
- tools/exports.pl --clean is no more removing Â
- authority search plugins is no more removing Â

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>