Optimize wxPGChoices::Set method.

There is no need to check if referenced array with values is 
valid since "reference cannot be bound to dereferenced null pointer in well-defined C++ code".
Moreover, conditional call of Add() methods(one with explicit parameter and one with default one) is not necessary.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78343 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/propgrid/property.h

@@ -1050,10 +1050,7 @@ public:
               const wxArrayInt& values = wxArrayInt() )
     {
         Free();
-        if ( &values )
-            Add(labels,values);
-        else
-            Add(labels);
+        Add(labels,values);
     }
 
     // Creates exclusive copy of current choices