smbd/smb2_ioctl: check sparseness for dup extents

smbd/smb2_ioctl: check sparseness for dup extents

FSCTL_DUPLICATE_EXTENTS_TO_FILE should fail if the source is marked
sparse while the target is not:

From: Jeff McCashland
To: David Disseldorp
Subject: RE: FSCTL_DUPLICATE_EXTENTS_TO_FILE questions, 116092214702946
Date: Tue, 27 Dec 2016 18:06:14 +0000

...
We have updated the spec for future release:

Section 2.3.8 FSCTL_DUPLICATE_EXTENTS_TO_FILE Reply
Changed description of STATUS_NOT_SUPPORTED error code to:
"--The source and target destination ranges overlap on the same file.
--Source file is sparse, while -target is a non-sparse file.
--The source range is beyond the source file's allocation size."

Signed-off-by: David Disseldorp <ddiss@samba.org>
Reviewed-by: Ralph Böhme <slow@samba.org>