[Ada] Cleanups related to building of dispatch tables

[Pierre-Marie de Rodat]

Code cleanup only; semantics is unaffected.

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

gcc/ada/

        * exp_ch7.adb (Expand_N_Package_Declaration): Fix wording in
        comment.
        * exp_disp.adb (Mark_DT): Remove unnecessary initialization of
        I_Depth.
diff --git a/gcc/ada/exp_ch7.adb b/gcc/ada/exp_ch7.adb
--- a/gcc/ada/exp_ch7.adb
+++ b/gcc/ada/exp_ch7.adb
@@ -6067,7 +6067,7 @@ package body Exp_Ch7 is
          Pop_Scope;
       end if;
 
-      --  Build dispatch tables of library level tagged types
+      --  Build dispatch tables of library-level tagged types
 
       if Tagged_Type_Expansion
         and then (Is_Compilation_Unit (Id)


diff --git a/gcc/ada/exp_disp.adb b/gcc/ada/exp_disp.adb
--- a/gcc/ada/exp_disp.adb
+++ b/gcc/ada/exp_disp.adb
@@ -4712,7 +4712,7 @@ package body Exp_Disp is
       Exname             : Entity_Id;
       HT_Link            : Entity_Id;
       ITable             : Node_Id;
-      I_Depth            : Nat := 0;
+      I_Depth            : Nat;
       Iface_Table_Node   : Node_Id;
       Name_ITable        : Name_Id;
       Nb_Prim            : Nat := 0;