Abstract i386_dr_low access

Abstract i386_dr_low access

This commit adds macros to abstract access to the i386_dr_low
function vector used by i386-nat.c.  The macros are named so
as to match the names of the functions that do the same work
in gdbserver.

gdb/
2014-06-18  Gary Benson  <gbenson@redhat.com>

	* i386-nat.c (i386_dr_low_can_set_addr): New macro.
	(i386_dr_low_can_set_control): Likewise.
	(i386_dr_low_set_addr): Likewise.
	(i386_dr_low_set_control): Likewise.
	(i386_dr_low_get_addr): Likewise.
	(i386_dr_low_get_status): Likewise.
	(i386_dr_low_get_control): Likewise.
	(i386_insert_aligned_watchpoint): Use new macros.
	(i386_update_inferior_debug_regs): Likewise.
	(i386_stopped_data_address): Likewise.

gdb/gdbserver/
2014-06-18  Gary Benson  <gbenson@redhat.com>

	* i386-low.c (i386_dr_low_can_set_addr): New macro.
	(i386_dr_low_can_set_control): Likewise.
	(i386_insert_aligned_watchpoint): New check.