Bug 16599: Fix XSS in opac-shareshelf.pl

Bug 16599: Fix XSS in opac-shareshelf.pl

Test plan:
- Create a list with the name "<script>alert(1)</script>"
- On the shelf list, click on share
=> Without this patch you will see the JS alert
=> With this patch applied you won't see it

Reported by Kaybee at Dionach

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>
(cherry picked from commit a44a930c076fceca0f7193f488e187d9849f89b6)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>