gas-test target

[Dave Brolley]

Doug Evans wrote:
> 
> Ben Elliston writes:
>  > In the cgen Makefile, it seems like an obvious enhancement is to run the
>  > generated `gas-build.sh' script from the `gas-test' target.  Is there any
>  > reason why this isn't done automatically?  If not, I'll submit a patch.
> 
> Because I didn't want to do that.
> I wanted to first inspect the result, then run it by hand.
> I'd mull this over for awhile before checking it in.

At the very least we need to be able to run it after hand
tweaking it. This is the way I add scenarios to the test, since
tweaking both the allinsn.s and allinsn.d files (especially the
second) can be a major hassle. So all I ask is that we end up
with a separate target to run it without regenerating it.

Dave