Bug#993107: theano: autopkgtest depends on libclblas-dev which is not in testing *and* has skip-not-installable

[Rebecca N. Palmer]

Control: tags -1 pending

This is the same underlying problem as #992673, but for this one it 
looks like switching to clblast is enough to pass the tests we actually 
run.  (Which isn't all of them because the GPU part of theano has never 
fully worked under OpenCL, but we already warn the user about that.)