Only define loff_t for __USE_MISC (bug 14553)

[Florian Weimer]

On 02/01/2018 09:36 PM, Joseph Myers wrote:
> 	[BZ #14553]
> 	* posix/sys/types.h (loff_t): Only define for [__USE_MISC].
> 	* sysdeps/unix/sysv/linux/sys/quota.h (dqoff): Use __loff_t
> 	instead of loff_t.

Looks okay.

Thanks,
Florian