In most places where pointer can be an 'error' it cannot be null
pointer. Further, in those cases just calling PTR_ERR() is not enough
to handle the null case. Simplify code by removing this case.
If NULL case needs to be handled, it's better to add separate check
and return fixed error code in that case.
- apk_istream_splice usage is converted to apk_stream_copy which
is the newer variant. With caching enabled by default, this
makes more sense mmapping or using separate buffers.
- apk_istream_tee is reworked to write to apk_ostream, which simplifies
quite a bit of various things
Timo Teräs