Bug#1086472: marco FTBFS on 32-bit with 64-bit time_t with gcc 14

[Bastian Germann]

Control: clone -1 -2
Control: reassign -2 libstartup-notification0-dev

Please change sn_startup_sequence_get_last_active_time (and for
consistency, sn_startup_sequence_get_initiated_time as well) argument *tv_sec
to have a time_t type so it can be used properly on 32 bit systems with
time_t being 64 bit wide, which is the configuration for armel and armhf
release architectures.