libbpf: Fix printing of ulimit value

Naresh pointed out that libbpf builds fail on 32-bit architectures because
rlimit.rlim_cur is defined as 'unsigned long long' on those architectures.
Fix this by using %zu in printf and casting to size_t.

Fixes: dc3a2d25 ("libbpf: Print hint about ulimit when getting permission denied error")
Reported-by: NNaresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: NToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191219090236.905059-1-toke@redhat.com

tools/lib/bpf/libbpf.c

@@ -117,7 +117,7 @@ static void pr_perm_msg(int err)
 		return;
 
 	if (limit.rlim_cur < 1024)
-		snprintf(buf, sizeof(buf), "%lu bytes", limit.rlim_cur);
+		snprintf(buf, sizeof(buf), "%zu bytes", (size_t)limit.rlim_cur);
 	else if (limit.rlim_cur < 1024*1024)
 		snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024);
 	else