ggml: Check return status for computation.

We don't check the return status after computing the graph, which
can silently lead to bad outputs if we try to keep going and future
computation succeeds. This appears to happens in certain cases on
Apple M2 devices.

Fixes #11070

ml/backend/ggml/ggml.go

@@ -602,7 +602,9 @@ func (c *Context) Forward(tensors ...ml.Tensor) ml.Context {
 }
 
 func (c *Context) Compute(tensors ...ml.Tensor) {
-	C.ggml_backend_sched_graph_compute_async(c.b.sched, c.graph)
+	if status := C.ggml_backend_sched_graph_compute_async(c.b.sched, c.graph); status != C.GGML_STATUS_SUCCESS {
+		panic(fmt.Errorf("error computing ggml graph: %v", status))
+	}
 	C.ggml_backend_sched_reset(c.b.sched)
 
 	needSync := true