uss: CIFS gives error while accessing .snaps directory

CIFS sends getxattr call while accessing .snaps directory.
snapview server should return ENODATA if getxattr is called
on .snaps folder. Also flush on .snaps folder should be handled.

Windows client sends and getxattr call on the parent folder
of .snaps with a special key to get the real filename of a file.
This is used by samba to do case insensitive check of files.

Fixed few FreeBSD compilation error.

bug: 1168875

Change-Id: I74d5cb4419568c8ed8709ba6d1ddff0e41392204
Signed-off-by: Rajesh Joseph <rjoseph@redhat.com>
Reviewed-on: http://review.gluster.org/9211
Reviewed-by: Raghavendra Bhat <raghavendra@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>