```__neg__``` failing for empty arrays

Here's the MWE

```python
>>> import pycuda.autoinit
>>> import pycuda.gpuarray as gpuarray
>>> import numpy as np
>>> empty_array = np.array([])
>>> empty_array_gpu = gpuarray.to_gpu(empty_array)
>>> neg_empty_array = -empty_array # array([], dtype=float64)
>>> neg_empty_array_gpu = -empty_array_gpu # Fails
```

Here's the error trace

```bash
---------------------------------------------------------------------------
error Traceback (most recent call last)
Input In [17], in ()
----> 1 -gpuarray.to_gpu(a)

File ~/pycuda/pycuda/gpuarray.py:643, in GPUArray.__neg__(self)
641 def __neg__(self):
642 result = self._new_like_me()
--> 643 return self._axpbz(-1, 0, result)

File ~/pycuda/pycuda/gpuarray.py:468, in GPUArray._axpbz(self, selffac, other, out, stream)
463 raise RuntimeError(
464 "only contiguous arrays may " "be used as arguments to this operation"
465 )
467 func = elementwise.get_axpbz_kernel(self.dtype, out.dtype)
--> 468 func.prepared_async_call(
469 self._grid,
470 self._block,
471 stream,
472 selffac,
473 self.gpudata,
474 other,
475 out.gpudata,
476 self.mem_size,
477 )
479 return out

File ~/pycuda/pycuda/driver.py:626, in _add_functionality..function_prepared_async_call(func, grid, block, stream, *args, **kwargs)
620 raise TypeError(
621 "unknown keyword arguments: " + ", ".join(kwargs.keys())
622 )
624 from pycuda._pvt_struct import pack
--> 626 arg_buf = pack(func.arg_format, *args)
628 for texref in func.texrefs:
629 func.param_set_texref(texref)

error: required argument is not an integer
```