[Ada] AI12-0411: Add "bool" to Interfaces.C

[Ada] AI12-0411: Add "bool" to Interfaces.C

gcc/ada/

	* libgnat/i-c.ads (bool): New type.
	* libgnat/i-cexten.ads, libgnat/i-cexten__128.ads (bool): Now
	a subtype of Interfaces.C.bool.
	* libgnarl/s-interr__vxworks.adb (Interrupt_Manager): Qualify
	False.
	* libgnarl/s-interr.adb, libgnarl/s-interr__hwint.adb,
	libgnarl/s-tasini.adb, libgnarl/s-tasren.adb,
	libgnarl/s-tassta.adb, libgnarl/s-tpobmu.adb,
	libgnarl/s-tpobop.adb, libgnarl/s-tpopmo.adb: Replace
	Assert (False) by Assert (Standard.False).