Describe the bug

The default usage of -l set to cores makes building on my system slow, as it usually has a load of 2 or 3, so make will not start more than one or two builds, despite the fact that there are more than 2 cores idle, as the load probably is due to IO wait.

Therefore it would be nice to be able to deactivate -l without individually overriding individual derivations or disabling its usage completely in builds.