MAINT: Delete unused "src" clearing functions (#18347)

The existance of both src and dst clearing confused my quite a lot
and made me wonder how best to refactor it.  Turns out, we don't
actually *use* src clearing to begin with.

I think in the long run, we should use a unary clear function
(with or without move-references).  I am fine with calling that
through GetDTypeTransferFunction (for now), but if there is a need
to clear a "destination" (rather than NULL it as initalization),
that is best solved by a unary function.

Ideally, we create a unary `DType.__decref__ = ArrayMethod()`
in the (fairly short) run.  We currently have two places that can
clear an array `PyArray_XDECREF()` and the dtype "transfer" functions.
We should have only one place.

The version in the dtype-transfer code is the better one, but it
might have the flaw that its setup could fail in a low-memory
scenario, which would mean we would have to do a fatal error probably.

In any case, this simply deletes currently unused and privat cod,
which is always good in my book.

0 files changed, 0 insertions, 0 deletions