* admin/emake: Return the status code of make when the build fails.
Filter the output of emake *clean. Add three options --no-color
(useful for emake check for example), --no-check (useful for quicker
builds during development) and --no-fast.
* Makefile.in: Add some commentary about make bootstrap,
./configure -C and FASTo
(top_bootclean): Don't delete config.cache here.
(top_distclean): Delete it here instead.
(bootstrap-clean): Allow not deleting the cache file.
* admin/emake (cores): Adjust.
Recent changes have made etc/doc always be regenerated, so it's no
longer interesting. And all "git pull"s will make
INFO Scraping files for cal-loaddefs.el...
INFO Scraping files for cal-loaddefs.el...done
etc be output, so filter them, too.