ada: Fix bogus Constraint_Error for 'Wide_Wide_Value on wide enumeration literal

The problem is that 'Wide_Wide_Value is piggybacked on 'Value and the latter
invokes System.Val_Util.Normalize_String, which incorrectly normalizes the
input string in the presence of enumeration literals with wide characters.

gcc/ada/ChangeLog:
	PR ada/115507
	* exp_imgv.adb (Expand_Valid_Value_Attribute): Add actual parameter
	for Is_Wide formal in the call to Valid_Value_Enumeration_NN.
	(Expand_Value_Attribute): Likewise.
	* libgnat/s-vaen16.ads (Value_Enumeration_16): Add Is_Wide formal.
	(Valid_Value_Enumeration_16): Likewise.
	* libgnat/s-vaen32.ads (Value_Enumeration_32): Likewise.
	(Valid_Value_Enumeration_32): Likewise.
	* libgnat/s-vaenu8.ads (Value_Enumeration_8): Likewise.
	(Valid_Value_Enumeration_8): Likewise.
	* libgnat/s-valboo.adb (Value_Boolean): Pass True for To_Upper_Case
	formal parameter in call to Normalize_String.
	* libgnat/s-valcha.adb (Value_Character): Likewise.
	* libgnat/s-valuen.ads (Value_Enumeration): Add Is_Wide formal.
	(Valid_Value_Enumeration): Likewise.
	* libgnat/s-valuen.adb (Value_Enumeration_Pos): Likewise and pass
	its negation for To_Upper_Case formal in call to Normalize_String.
	(Valid_Value_Enumeration): Add Is_Wide formal and forward it in
	call to Value_Enumeration_Pos.
	(Value_Enumeration): Likewise.
	* libgnat/s-valuti.ads (Normalize_String): Add To_Upper_Case formal
	parameter and adjust post-condition accordingly.
	* libgnat/s-valuti.adb (Normalize_String): Add To_Upper_Case formal
	parameter and adjust implementation accordingly.
	* libgnat/s-valwch.adb (Value_Wide_Wide_Character): Pass False for
	To_Upper_Case formal parameter in call to Normalize_String.