Optionally remove portage files, so that we can cache package and
keep the portage directory around, specifically for nodepool.
This also adds a section to the Gentoo readme about the variable
and renames the 00-gentoo-distro-name environment file to a more
appropriate name of 00-gentoo-envars.
Also brought up was the location of the gentoo-releng.gpg file,
this has been moved and the refrencing paths updated.
Change-Id: I20c91b36082828faa1ca481585acc5f9933211e1
Gentoo provides eclean-dist via the gentoolkit package
eclean-dist isn't needed anyway was /usr/portage is removed anyway
Removed redundant package update in cleanup.
Change-Id: Icf4f9ed549b9a6d923448d927d7c42bcf8d6091b
This checks the profile, if it has hardened in it's name it needs xattr support
unfortunately xattr support cannot yet be relied on everywhere, so it needs to
be disabled for hardened profile builds to correctly pax-mark.
Change-Id: I7fb855249a9e6c9b6497ab5061b4ea3c014f5081
Closes-Bug: 1537177
