ada: Remove Is_Descendant_Of_Address flag from Standard_Address

It breaks the Allow_Integer_Address special mode.

Add new standard_address parameters to gigi and alphabetize others, this is
necessary when addresses are not treated like integers.

gcc/ada/

	* back_end.adb (Call_Back_End): Add gigi_standard_address to the
	signature of the gigi procedure and alphabetize other parameters.
	Pass Standard_Address as actual parameter for it.
	* cstand.adb (Create_Standard): Do not set Is_Descendant_Of_Address
	on Standard_Address.
	* gcc-interface/gigi.h (gigi): Add a standard_address parameter and
	alphabetize others.
	* gcc-interface/trans.cc (gigi): Likewise.  Record a builtin address
	type and save it as the type for Standard.Address.