[Ada] Remove redundant check for empty list

[Pierre-Marie de Rodat]

Cleanup only; semantics is unaffected.

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

gcc/ada/

        * sem_ch3.adb (Analyze_Declarations): Remove explicit check for
        missing, because a subsequent call to Is_Empty_List will detect
        them anyway.
diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -2758,7 +2758,6 @@ package body Sem_Ch3 is
                Resolve_Aspects;
 
             elsif L /= Visible_Declarations (Parent (L))
-              or else No (Private_Declarations (Parent (L)))
               or else Is_Empty_List (Private_Declarations (Parent (L)))
             then
                Adjust_Decl;