gallivm: Report the unsupported intrinsic instead of just assert(0);

Tripped over this in rendermode with softpipe NIR.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6567>
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_nir.c b/src/gallium/auxiliary/gallivm/lp_bld_nir.c
index bb04bee..f0f8a9c 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_nir.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_nir.c
@@ -1581,6 +1581,9 @@
       visit_interp(bld_base, instr, result);
       break;
    default:
+      fprintf(stderr, "Unsupported intrinsic: ");
+      nir_print_instr(&instr->instr, stderr);
+      fprintf(stderr, "\n");
       assert(0);
       break;
    }