i386 now has shared IRQ support

[sebastian.huber at embedded-brains.de (Sebastian Huber)]

Joel Sherrill wrote:
> Daron Chabot wrote:
>   
>> [...]
>>>   
>>>       
>> More than happy to:  I have absolutely no objections to throwing away
>> cludge-code !
>>   
>>     
>
> Now we need to follow that up by figuring out how to merge and
> shared the libbsp/powerpc/shared/irq and libbsp/i386/shared/irq
> irq.c files. :-D

Simply use the code in libbsp/shared/include/irq-*.h and 
libbsp/shared/src/irq-*.c.