The -j flag should only be submitted once. If we are enclosed by yet
another layer of makes, then it will have setup everything for this
sub-make to take part in the job pool.
If you run make with -n switch, it would just print the forwarding
command. Now it should continue into the original make, having that
one printing its actions as well.
We do dependency management the right way; there should be no need to
use ccache on top of this. Actually, it will just hurt performance to
do so without any win.
If we are building in a VM which doesn't have /proc mounted, then it is
most likely that this is done on a shared server; we revert to building
for a single processor.
