xen, x86 intr code rototil alert.

[Cherry G. Mathew <cherry%zyx.in@localhost>]

Hello,

As threatened earlier [1], I checked in a bunch of preparatory commits
for the big one - to overhaul our PV interrupt codepath and to unify it
with the x86/intr.c paths.

This would help abstract out several things, as well as make it much
easier for PVHVM to happen sanely.

I really would appreciate it if people would test Xen  -current on
amd64/i386 - dom0/domU and shout if anything is broken that wasn't
before these changes.

The last of them were made on 4th November.

The next change I make will really rock the boat hard, so I want to make
sure that people who are using / testing -current have had a chance to
test things out, before I commit to that change. All the previous
changes are revertable in the reverse order they were committed - they
are more-or-less self contained - I took pains to make sure this was the
case. 

Many Thanks,

[1] http://mail-index.netbsd.org/port-xen/2017/10/23/msg009096.html
-- 
~cherry