[Ada] gnatbind: do not list No_Implementation_Restrictions

[Ada] gnatbind: do not list No_Implementation_Restrictions

When the gnatbind -r switch is used, do not list
No_Implementation_Restrictions, because after using the new restriction list,
No_Implementation_Restrictions will cause an error.

2018-05-23  Bob Duff  <duff@adacore.com>

gcc/ada/

	* gnatbind.adb (List_Applicable_Restrictions): Add
	No_Implementation_Restrictions to the list of restrictions not to list.
	Remove double negative "not No_Restriction_List".  Comment the
	commentary that is output, so it won't cause errors if used directly in
	a gnat.adc.

From-SVN: r260593