[cmake] Increase the internet connection test timeout.
[cmake] Increase the internet connection test timeout.

The 5 second timeout was not enough when trying to build ROOT in docker.
Possibly the issue was due to lag on the server as well.

Patch by Alexander Penev (@alexander-penev).

olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root