[Ada] Fix missing error on actual for In/Out parameter

[Pierre-Marie de Rodat via Gcc-patches]

The compiler was failing to give an error on the result of a call to the
Input attribute passed as actual for an In/Out parameter.
Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * sem_util.adb (Is_OK_Variable_For_Out_Formal): Remove test on
        Comes_From_Source in the condition dealing with the expression
        of an N_Unchecked_Type_Conversion node.
diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -19533,9 +19533,7 @@ package body Sem_Util is
          if Nkind (Original_Node (AV)) in N_Function_Call | N_Aggregate then
             return False;
 
-         elsif Comes_From_Source (AV)
-           and then Nkind (Original_Node (Expression (AV))) = N_Function_Call
-         then
+         elsif Nkind (Original_Node (Expression (AV))) = N_Function_Call then
             return False;
 
          elsif Nkind (Original_Node (AV)) = N_Type_Conversion then