suzerain: #2818 siter, diter = 0 on no attempt

The API documentation said these would come back as the number of
iterations attempted.  When no iteration were attempted, they
were coming back as '-1' instead.  Update test_blas_et_al.c to
check this condition.  Update the dsgbsvx.def to set these to
'0' when no attempt is made.

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@43170 0bd85f0b-c151-43b9-a1e9-27231104551f