[Ada] Add stream-oriented attributes support for 128-bit integer types

[Ada] Add stream-oriented attributes support for 128-bit integer types

gcc/ada/

	* doc/gnat_ugn/building_executable_programs_with_gnat.rst (-xdr):
	Document that XDR is not supported for 128-bit integer types.
	* gnat_ugn.texi: Regenerate.
	* exp_strm.adb (Build_Elementary_Input_Call): Deal with types
	larger than Long_Long_Integer.
	(Build_Elementary_Write_Call): Likewise.
	* rtsfind.ads (RE_Id): Add RE_I_LLL{I,U] and RE_W_LLL{I,U}.
	(RE_Unit_Table): Add entries for them.
	* libgnat/s-stratt.ads (I_LLLI): New inline function.
	(I_LLLU): Likewise.
	(W_LLLI): New inline procedure.
	(W_LLLU): Likewise.
	* libgnat/s-stratt.adb (S_LLLI): New subtype of SEA.
	(S_LLLU): Likewise.
	(From_LLLI): New instance of Unchecked_Conversion.
	(From_LLLU): Likewise.
	(To_LLLI): Likewise.
	(To_LLLU): Likewise.
	(I_LLLI): Implement.
	(I_LLLU): Likewise.
	(W_LLLI): Likewise.
	(W_LLLU): Likewise.