By using --cores argument to rootfs.py, JOBS= is set in the
live-bootstrap environment, and -j${JOBS} is used on builds. This speeds
larger packages up significantly.
A fair number of packages do not build properly with parallelism. Most
of these, at least for now, are disabled with -j1.
Also remove redundant autotools stages.
Early manpages in autoconf 2.52-2.59 are removed from output.
Later ones are regenerated with help2man.
Fixes#182