site.c: Make sure there's enough buffer space for the signature terminator.

[secnet] / test-example / memcheck.suppressions

{
   secnet_read_conffile
   Memcheck:Leak
   ...
   fun:read_conffile
   fun:main
}
{
   secnet_enter_phase
   Memcheck:Leak
   ...
   fun:enter_phase
   fun:main
}