Update for mantis 2817: this is a better way of removing extra popups
There are more types of campaign load failures than just missing campaign files

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9606 387891d4-d844-0410-90c0-e4c51a9137d3
Fix for Mantis 2823: AddressSanitizer: global-buffer-overflow in hud_escort_ship_hit()

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@9607 387891d4-d844-0410-90c0-e4c51a9137d3