s3: VFS: streams_xattr: Add the same accommodation to streams_xattr_unlinkat() as...

s3: VFS: streams_xattr: Add the same accommodation to streams_xattr_unlinkat() as used in streams_xattr_renameat().

vfs_fruit passes a synthetic filename here where smb_fname->fsp==NULL
when configured to use "fruit:resource = stream" so we need to use
synthetic_pathref() to get an fsp on the smb_fname->base_name
in order to call SMB_VFS_FREMOVEXATTR().

This is the same change we already use in streams_xattr_renameat()
and streams_xattr_stat(), the other pathname operations we implement
here.

Remove knownfail.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15099

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Noel Power <npower@samba.org>
Autobuild-User(master): Noel Power <npower@samba.org>
Autobuild-Date(master): Mon Jun 20 14:24:20 UTC 2022 on sn-devel-184