[Ada] Fix inconsistent comment about expansion of exception declarations

[Pierre-Marie de Rodat via Gcc-patches]

Code cleanup.

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

gcc/ada/

        * exp_ch11.adb (Expand_N_Exception_Declaration): Sync comment
        with declaration in System.Standard_Library.
diff --git a/gcc/ada/exp_ch11.adb b/gcc/ada/exp_ch11.adb
--- a/gcc/ada/exp_ch11.adb
+++ b/gcc/ada/exp_ch11.adb
@@ -1136,7 +1136,7 @@ package body Exp_Ch11 is
       Set_Is_Statically_Allocated (Ex_Id);
 
       --  Create the aggregate list for type Standard.Exception_Type:
-      --  Handled_By_Other component: False
+      --  Not_Handled_By_Others component: False
 
       L := Empty_List;
       Append_To (L, New_Occurrence_Of (Standard_False, Loc));