Fix cli_splice() fallback code when splicing less than a complete file.

[David Disseldorp]

On Thu, 12 Jul 2018 13:08:19 -0700, Jeremy Allison wrote:

> Bailey Berro <baileyberro at google.com> found bug:
> 
> https://bugzilla.samba.org/show_bug.cgi?id=13527
> 
> where the fallback code for cli_splice() is always
> asking for SPLICE_BLOCK_SIZE even when the
> remaining bytes we need were smaller than that. This works
> when using cli_splice() on a complete file, as the cli_read()
> terminated the read at the right place.
> 
> Includes regression test and fix. Passes local
> make test, and is in gitlab-CI:
> 
> https://gitlab.com/samba-team/devel/samba/pipelines/25667214
> 
> Please review and push if happy !

Looks good, thanks for adding test coverage. Pushed to autobuild.

Cheers, David