Function usage

lib_acl_cpp/samples/thread_pool/main.cpp:178–183

//////////////////////////////////////////////////////////////////////////

static void usage(const char* proc)
{
	printf("usage: %s -h [help]\r\n"
		"	-c which_case [0, 1, 2, 3, 4, 5]\r\n",
		proc);
}

int main(int argc, char* argv[])
{