20041007, danarmak:
	* ported stuart's orig patch to portage .51_rc7
	* change: move the confcache code in econf into new functions confcache_start(),
		confcache_stop(), which are called at the beginning and end of econd().
		this way ebuilds that don't use econf (eg kde.eclass) can still use confcache explicitly.
	* fix: confcache_stop: also remove allowed chown()s from sandbox log
	* fix: confcache_stop: fix sed invocations
	* optimize: confcache_stop: convert many sed invocations into one invocation with many scripts
		(can be further reduced to egrep()s, but i'm lazy and this seems fast enough)
	* change: move cache to PORTAGE_TMPDIR. /etc/portage is obviously the wrong place, and carpaski
		advises not using /var/cache/edb like ferringb did as long as the implementation is in bash
		and runs under the sandbox.
	* change: store separate cache per combinations of $CHOST, $CBUILD, $TBUILD, as in ferringb's version;
		the embedded people are said to want this