ARM HAL exception handling

[Mark Salter]

>>>>> Jonathan Larmour writes:

> Andrew Lunn wrote:
>> Hi folks
>> 
>> I don't know enough about thumb to deal with this patch. Please can
>> someone else take a look.

> Mark's the expert on this stuff AFAIK, but firstly it mostly only affects 
> #ifdef  CYGHWR_HAL_ARM_DUMP_EXCEPTIONS stuff, so can't be too problematic. 
> Clearly the current stuff doesn't grok thumb at all. The change looks 
> reasonable.

Yes, I agree. The changes look right to me. 

--Mark