Remove -gnatd.O doc

From-SVN: r149676

gcc/ada/debug.adb

@@ -132,7 +132,7 @@ package body Debug is
    --  d.L
    --  d.M
    --  d.N
-   --  d.O  Dump internal SCO table
+   --  d.O
    --  d.P
    --  d.Q
    --  d.R
@@ -559,8 +559,6 @@ package body Debug is
    --       byte code, even in case of unsupported construct, for the sake
    --       of static analysis tools.
 
-   --  d.O  Dump internal SCO (Source Coverage Obligation) table in Par_Sco
-
    --  d.S  Force Optimize_Alignment (Space) mode as the default
 
    --  d.T  Force Optimize_Alignment (Time) mode as the default