For now, only the non-standard _SC_NPROCESSORS_CONF and
_SC_NPROCESSORS_ONLN are implemented.
Use them to make ninja pick a better default -j value.
While here, make the ninja package script not fail if
no other port has been built yet.
- 1.8.2 for now, newer versions need high-res timestamp file APIs
which serenity doesn't have yet
- pselect() instead of ppoll() for now, same reason (depends on #2609)
- no good default for -j yet (see nproc.patch)
- `-l` probably doesn't work yet (see loadavg.patch), but I've never
used that anyways
- some minor include patches that I've also sent upstream
Other than that, this seems to work reasonably well. It currently
produces some spam on stdout from probably the shell.
