add wxUSE_WEAKREF (modified partially applied patch 1870445)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@51614 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/os2/setup0.h

@@ -234,6 +234,16 @@
 // Recommended setting: 0 unless you do plan to develop MT applications
 #define wxUSE_THREADS 1
 
+// Set wxUSE_WEAKREF to 1 t support use of weak references to common classes
+// in wxWidgets (wxWeakRef<T>). Set to 0 if your compiler has problems with
+// the template-based implementation (Embedded Visual C++ 4 for ARM has a bug
+// in this area, Visual C compiler options "/vmm /vmg" may help then).
+//
+// Default is 1
+//
+// Recommended setting: 1
+#define wxUSE_WEAKREF 1
+
 // If enabled, compiles wxWidgets streams classes
 //
 // wx stream classes are used for image IO, process IO redirection, network