virtlogd: use %llu to print 64bit types

virtlogd: use %llu to print 64bit types

Otherwise we fail on 32bit with:

CC     logging/virtlogd-log_daemon_dispatch.o
logging/log_daemon_dispatch.c: In function 'virLogManagerProtocolDispatchDomainReadLogFile':
logging/log_daemon_dispatch.c:120:9: error: format '%zu' expects argument of type 'size_t', but argument 7 has type 'uint64_t' [-Werror=format]