gas-test target

[Doug Evans]

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.