Add fcntl sealing interfaces from Linux 3.17 to bits/fcntl-linux.h

[Paul Eggert]

On 09/08/2017 09:16 AM, Joseph Myers wrote:
> glibc tends to use the "Likewise." style more than is required by the GNU
> Coding Standards; I'm not sure why.

It's inertia. As I recall the GNU Coding Standards formerly recommended 
"Likewise", and they still have a circa-1998 example using it 
(unnecessarily, I might add). This was before they extended ChangeLog 
format to make "Likewise" largely unnecessary.