discoverer: add casts to avoid warnings in osx builds
Fix the following warnings by adding casts.
gstdiscoverer.c:1801:17: error: format specifies type 'unsigned long' but the argument has type 'off_t' (aka 'long long') [-Werror,-Wformat]
location, file_status.st_size, file_status.st_mtime);
^~~~~~~~~~~~~~~~~~~
gstdiscoverer.c:1801:38: error: format specifies type 'long long' but the argument has type '__darwin_time_t' (aka 'long') [-Werror,-Wformat]
location, file_status.st_size, file_status.st_mtime);
Edited by Josep Torra