Integrals over single basis functions

[obackhouse]

I'd like to compute integrals of the form

$$ \int \frac{\phi_p(\mathbf{r})}{\vert \mathbf{r} - \mathbf{r}_x \vert} \mathrm{d}\mathbf{r} $$

which is pretty much just an int1e_rinv with a single basis function instead of a pair. I tried to do this via the PySCF interface by creating a dummy molecule with a single diffuse S function on a ghost atom and using intor_cross but don't seem to be getting what I need. Can I do this directly via libcint?