Change maybe_disable_address_space_randomization to a class

Change maybe_disable_address_space_randomization to a class

This changes maybe_disable_address_space_randomization to be an RAII
class, rather than having it return a cleanup.

Regression tested by the buildbot.

ChangeLog
2017-11-26  Tom Tromey  <tom@tromey.com>

	* nat/linux-personality.h (class
	maybe_disable_address_space_randomization): New class.
	(maybe_disable_address_space_randomization): Don't declare
	function.
	* nat/linux-personality.c (restore_personality)
	(make_disable_asr_cleanup): Remove.
	(maybe_disable_address_space_randomization): Now a constructor.
	(~maybe_disable_address_space_randomization): New destructor.
	* linux-nat.c (linux_nat_create_inferior): Update.

gdbserver/ChangeLog
2017-11-26  Tom Tromey  <tom@tromey.com>

	* linux-low.c (linux_create_inferior): Update.