mod_mailinglist: Only show addresses in bounce dialog for the current mailing page

This way, the number in the overview (http://stick.im/s/u5a)
always corresponds to the number of rows in the bounce dialog. (http://stick.im/s/LW8)
(cherry picked from commit 0a06526d2423ab17f11ef43acf5dcb5e95d78c0a)