Emba/Gitlab tests

[Alan Third]

I was looking at the tests running on emba.gnu.org and had the idea that it
might make sense to add a simple build job to build against GNUstep
when any of the NS files are modified.

I don't think it would be worth running the test suite against it, but
it would still be potentially useful to know that the GNUstep build
isn't completely broken.

Does that sound OK, or are there any concerns about running too many
jobs?
-- 
Alan Third