set a more reasonable default for number of jobs

Instead of just one use four jobs by default, which is a more reasonable default these days. The worst that can^w should happen is some performance drop due to increased concurrency in setups with less than four CPU cores.

Maybe this should just default to the value that 'nproc' or nproc '--all' return. But I guess there was a reason why this was not done in the first place, so I stayed away from that path (for now!)

Signed-off-by: Thorsten Leemhuis fedora@leemhuis.info

Signed-off-by: Patrick Talbert ptalbert@redhat.com