MAKEDEV call, add autodev hooks, add environment variables for hook scripts.

MAKEDEV call, add autodev hooks, add environment variables for hook scripts.

Ok...  Here's the patch again.  Since Serge is removing the loglevel
structure member, this patch no longer references that element.

From the original description:

1) Removes run_makedev() and the call to it from conf.c per discussion.

2) Adds an lxc.hook.autodev hook.

Note: This hook is very close (one routine level abstracted) from where
the run_makedev was called.  Anyone really rrreeeaaalllyyy needing
MAKEDEV can add it in with a small shim script to do whatever they want
under whatever distro they're using, so no functionality is lost there.

3) Added a number of environment variables for all the hook scripts to
reference to assist in execution.  Things like LXC_ROOTFS_MOUNT could be
very useful but others were added as well.  Room for more if anyone has
an itch.  All in one spot in lxc_start.c.

4) clearenv and putenv( "container=lxc" ) calls were moved to just after
the "start" hook in the container just prior to actually firing up the
container so we could use environment variables prior to that and have
them flushed them before firing up init.  Nice side effect is that you
can define environment variables and then call lxc-start and have them
show up in those hooks scripts.

5) I actually DID update the man page for lxc.conf!  I guess I lied when
I said I wouldn't get that done.

[... and ...]

I added the rcfile to the lxc_conf structure as suggested and moved the
setenv bundle from lxc-start.c over to start.c just prior to calling
run_lxc_hooks for the pre-start hook.

Signed-off-by: Michael H. Warfield <mhw@WittsEnd.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>