[Bug ada/123003] missing warning for unused use clause when use clause for child package is present

[jesper.quorning at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123003

--- Comment #3 from Jesper Quorning <jesper.quorning at gmail dot com> ---
Following program emits false positives:

```ada

with Ada.Text_IO;

procedure Program_2
is
   use Ada;
   use Text_IO;

   procedure P (Item : String)
     renames Put_Line;

begin
   P ("Greetings");
end Program_2;
```

Building:

$ gnatmake -gnatwu program_2.adb
gcc -c -gnatwu program_2.adb
program_2.adb:5:04: warning: use clause for package "Ada" has no effect
[-gnatwu]
program_2.adb:6:04: warning: use clause for package "Text_IO" has no effect
[-gnatwu]
gnatbind -x program_2.ali
gnatlink program_2.ali


Expected:
No warnings.


Thanks