Do not add a an extraneous /etc/static layer of indirection.
* gnu/build/activation.scm (activate-etc) <realpath>: New nested procedure.
Do not create /etc/static. Symlink instead of copy all files under /etc,
except for /etc/sudoers.
Change-Id: I8ea16d07de256482efac37d2ff9482a5f56bd585
Reviewed-by: Ludovic Courtès <ludo@gnu.org>