[PATCH 1/2][ARC] Add support for ARCv2 CPUs

[Claudiu Zissulescu]

This patch is committed (without the gen_compare_reg change). 

Thanks Joern,
Claudiu

> Apart from the gen_compare_reg change, the patch is OK.
> If the v2 support mostly works like support for the other subtargets, you may
> check it in without the gen_compare_reg change.
> If that change is required because of particular code paths taken with the v2
> port, you may check in the whole patch.
> 
> The operand-swapping in gen_compare_reg was not expected to be
> triggered when re-generating a comparison, as comparisons gleaned from
> existing instructions are supposed to already have the operands in the right
> order.
> Do you have a testcase that triggers the assert independently from the
> v2 support?
> If you can name a pre-existing testcase to trigger the assert, the patch is
> approved for separate check-in.
> If you have a new testcase, is it in a form and of a legal status that it can be
> submitted for inclusion in the gcc regression tests suite?