fix warning about unused rc variable in release builds

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@46108 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/stack.h

@@ -20,8 +20,10 @@ class cls : public wxVectorBase\
 public:\
     void push(const obj& o)\
     {\
-        bool rc = Alloc(size() + 1);\
+        if ( !Alloc(size() + 1) )\
-        wxASSERT(rc);\
+        {\
+            wxFAIL_MSG(_T("failed to extend stack"));\
+        }\
         Append(new obj(o));\
     };\
 \