[Ada] Remove explicit "in" in internal parameter association

[Pierre-Marie de Rodat via Gcc-patches]

Code cleanup related to expansion of dispatching routines for GNATprove.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * exp_attr.adb (Build_Array_VS_Func): Remove explicit "IN" in
        spec of the generated array validation function; it was
        redundant, just like it would be in a user-written code.
diff --git a/gcc/ada/exp_attr.adb b/gcc/ada/exp_attr.adb
--- a/gcc/ada/exp_attr.adb
+++ b/gcc/ada/exp_attr.adb
@@ -404,8 +404,6 @@ package body Exp_Attr is
               Parameter_Specifications => New_List (
                 Make_Parameter_Specification (Loc,
                   Defining_Identifier => Obj_Id,
-                  In_Present          => True,
-                  Out_Present         => False,
                   Parameter_Type      => New_Occurrence_Of (Formal_Typ, Loc))),
               Result_Definition        =>
                 New_Occurrence_Of (Standard_Boolean, Loc)),