minios: Revert recent change and revert to working minios

minios: Revert recent change and revert to working minios

Currently, xen.git#staging does not build in many environments because
of issues with minios master.  This regression was introduced in an
uncontrolled manner by an update to mini-os.git#master.

This is because in e013e8514389 "config: use mini-os master for
unstable" we switched to tracking minios master in an uncontrolled
manner.  At the time we thought it was unlikely that minios changes
would break the Xen build.  This turns out to have been overly
optimistic.

Xen currently uses unstable internal interfaces of minios.  Until this
can be sorted out, internal changes to minios can require lockstep
changes in Xen.

All this means that "config: use mini-os master for unstable" was
wrong.  We should undo it.  Instead, we go back to the previous
situation: xen.git names a specific minios commit.

This scheme is the model used for qemu-xen-traditional.

That nailed commit must be updated manually, to have xen.git pick up
changes from minios.  If the minios changes require changes in xen.git
too, to avoid breaking the Xen build, they can be made freely in
minios without adverse consequences.  When the minios commitid is
updated in xen.git, the corresponding changes to the actual source
files in xen.git should be bundled together.

For example, when minios is fixed, 8d990807ec2c "stubdom/grub: update
init_netfront() call for mini-os" will need to be reapplied, folded
into the same commit as updates MINIOS_UPSTREAM_REVISION.  For now
that commit must be reverted as we are going back to a previous
version of minios.

This reverts commit 8d990807ec2cde3061222a5ed2df62aba78bace9.
This reverts commit e013e8514389b739153016349e49f5a78e34ddf0.

CC: Jan Beulich <jbeulich@suse.com>
CC: Costin Lupu <costin.lupu@cs.pub.ro>
CC: Wei Liu <wl@xen.org>
CC: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Ian Jackson <iwj@xenproject.org>