[gcc r12-4388] [Ada] reenable ada83 library unit renaming error

[Alexandre Oliva]

https://gcc.gnu.org/g:ee9fa8a57920e6ceb49bbf0929604a34ee5cabb4

commit r12-4388-gee9fa8a57920e6ceb49bbf0929604a34ee5cabb4
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Thu Oct 14 01:49:44 2021 -0300

    [Ada] reenable ada83 library unit renaming error
    
    for  gcc/ada/ChangeLog
    
            * par-ch10.adb (P_Compilation_Unit): Reenable ada83 library
            unit renaming test and error.

Diff:
---
 gcc/ada/par-ch10.adb | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/gcc/ada/par-ch10.adb b/gcc/ada/par-ch10.adb
index f02934afc7e..76f0edddc94 100644
--- a/gcc/ada/par-ch10.adb
+++ b/gcc/ada/par-ch10.adb
@@ -532,13 +532,14 @@ package body Ch10 is
                                | N_Subprogram_Body
                                | N_Subprogram_Renaming_Declaration
          then
-            Unit_Node := Specification (Unit_Node);
-
-         elsif Nkind (Unit_Node) = N_Subprogram_Renaming_Declaration then
-            if Ada_Version = Ada_83 then
+            if Nkind (Unit_Node) = N_Subprogram_Renaming_Declaration
+              and then Ada_Version = Ada_83
+            then
                Error_Msg_N
                  ("(Ada 83) library unit renaming not allowed", Unit_Node);
             end if;
+
+            Unit_Node := Specification (Unit_Node);
          end if;
 
          if Nkind (Unit_Node) in N_Task_Body