A patch to simplify the MD interrupt code a bit..

[Sam Leffler]

John Baldwin wrote:
> This patch adds an MI intr_event_handle() routine for the non-FILTER case so 
> that the MD code becomes identical in both cases and all the INTR_FILTER 
> #ifdef's end up in kern_intr.c.  It's been tested on amd64, i386, and sparc64 
> and cross-compiled on ppc, arm, and ia64.  I'd like to get it tested on arm 
> as I slightly adjusted the MD code to just not bother masking the interrupt 
> unless we are going to run an ithread which is mostly what the existing 
> FILTER code did except that it unmasked the interrupt when it wasn't masked 
> in the first place if a filter handled the interrupt.  Patch is at 
> http://www.freebsd.org/~jhb/patches/intr_filter.patch
>
>   
Seems to be ok on an AVILA board w/ latest HEAD.

    Sam