[Numpy-discussion] A zeros_like implementation based on calloc instead of copyto

[Mark Harfouche]

Hello,

Currently, `zeros_like` is based `copyto` as opposed to `calloc`.
This causes inconsistencies in the amount of time it takes to create an
array with `zeros` + `shape` and `zeros_like` for large arrays.
This was first raised https://github.com/numpy/numpy/issues/9909

It seems to me that a memory copy can be avoided by using
`PyArray_NewFromDescr_int`
in C.

I propose creating a new C_API function `PyArray_NewZerosLikeArray` that
behaves much like the `PyArray_NewLikeArray` with the exception that it
calls
`PyArray_NewFromDescr_int` instead of `PyArray_NewFromDescr` to initialize
the array to zeros with calloc.

An all C implementation of `zeros_like` is also possible by adapting the
`empty_like` function.

A draft implementation is viewable
https://github.com/hmaarrfk/numpy/pull/2/files for those looking for more
details about my proposed implementation.

Thank you for considering.

Mark
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