Compiling with clang gives a format warning like
iscsi-perf.c:98:53: error: format specifies type 'unsigned long' but the
argument has type 'uint64_t' (aka 'unsigned long long')
[-Werror,-Wformat]
so replace %lu with %llu where appropriate.
Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>