select: switch select() and poll() over to hrtimers

With lots of help, input and cleanups from Thomas Gleixner

This patch switches select() and poll() over to hrtimers.

The core of the patch is replacing the "s64 timeout" with a
"struct timespec end_time" in all the plumbing.

But most of the diffstat comes from using the just introduced helpers:
	poll_select_set_timeout
	poll_select_copy_remaining
	timespec_add_safe
which make manipulating the timespec easier and less error-prone.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>