[Ada] Clean up support for validity checks in the compiler

[Ada] Clean up support for validity checks in the compiler

This removes old code in the parser that serves no useful purpose and
fixes minor issues in the Validsw package.  No functional changes.

2019-07-04  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* gnat1drv.adb (Adjust_Global_Switches): Use proper interface to
	set the validity settings in CodePeer mode.
	* par-load.adb (Load): Remove all code dealing with validity
	settings.
	* validsw.ads (Validity_Check_Copies): Alphabetize.
	* validsw.adb (Reset_Validity_Check_Options): Set all options to
	off.
	(Save_Validity_Check_Options): Save all options.

From-SVN: r273071