Bug 36532: Protect opac-dismiss-message.pl from malicious usages

Bug 36532: Protect opac-dismiss-message.pl from malicious usages

Really bad design, NEVER retrieve the logged in user from the CGI
param!

See comment 1 for more info

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: David Cook <dcook@prosentient.com.au>
(cherry picked from commit a40e1fd62c7320ad5f7b8514ba2bd129aad2d10f)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit 1df8ee19943b6d112eba85bbab308ba8b550ed67)
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>