ggml-alloc: Don't try to re-use buffers of external tensors (#2562) * ggml-alloc: Don't try to re-use buffers of external tensors They might be weights that came from another context, so we have no control over them (and they might be re-used elsewhere so writing to them would be a bad idea). * ggml-alloc: >= when checking for out-of-bounds Co-authored-by: slaren <[email protected]> --------- Co-authored-by: slaren <[email protected]>