Add flag in gpr to support in and out params in interfaces

src/polyorb_hi.gpr.in

@@ -69,7 +69,8 @@ project PolyORB_HI is
                       --@WARNINGS_ARE_ERRORS@"-gnatwe", --  Warnings are errors
                       "-gnatwG", -- Suppress warnings on unrecognized pragmas
                       "-gnat12", --  Ada 2012 mode
-                      "-fstack-usage"  -- Report stack usage
+                      "-fstack-usage",  -- Report stack usage
+                      "-gnatd.E"  -- Allow In and Out params to be the same variable
                      );
 
    Debug_Options := (