[Ada] Remove repeated setting of Never_Set_In_Source

[Pierre-Marie de Rodat via Gcc-patches]

Formal parameters have their flag Never_Set_In_Source set at the
beginning of Process_Formals routine (regardless of the parameter mode).
There is no need to set it again when Process_Formals calls
Set_Formal_Mode (for parameters of mode IN OUT and OUT).

Code cleanup related to improved detection of uninitialised objects;
behaviour is unaffected.

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

gcc/ada/

        * sem_ch6.adb (Set_Formal_Mode): Remove unnecessary setting of
        Never_Set_In_Source.
diff --git a/gcc/ada/sem_ch6.adb b/gcc/ada/sem_ch6.adb
--- a/gcc/ada/sem_ch6.adb
+++ b/gcc/ada/sem_ch6.adb
@@ -13298,10 +13298,9 @@ package body Sem_Ch6 is
             Mutate_Ekind (Formal_Id, E_In_Out_Parameter);
 
          else
-            Mutate_Ekind            (Formal_Id, E_Out_Parameter);
-            Set_Never_Set_In_Source (Formal_Id, True);
-            Set_Is_True_Constant    (Formal_Id, False);
-            Set_Current_Value       (Formal_Id, Empty);
+            Mutate_Ekind         (Formal_Id, E_Out_Parameter);
+            Set_Is_True_Constant (Formal_Id, False);
+            Set_Current_Value    (Formal_Id, Empty);
          end if;
 
       else