fixed init log

With latest master I've noticed invalid messages during uWSGI startup:

```mapped 127728 bytes (0 KB) for 124 cores```

Just look at travis log: https://travis-ci.org/prymitive/uwsgi/jobs/4123644/#L605

Travis builds uWSGI with 32 bit Ubuntu, so it looks like it's just wrong log format, I've substituted ```%lu``` with ```%llu``` and it seems to be working fine under both 32 and 64 bit, but AFAIK casting it to ```unsigned long long``` is a proper solution, so this is what I did.

But the ugly part is that (u)int64_t requires different log format depending on the arch so there might be places where such casting is still needed.