Teach Windows build about the _weakref module.
diff --git a/Modules/_weakref.c b/Modules/_weakref.c
index 3c03c3c..dcbcb6b 100644
--- a/Modules/_weakref.c
+++ b/Modules/_weakref.c
@@ -728,7 +728,7 @@
 };
 
 
-void
+DL_EXPORT(void)
 init_weakref(void)
 {
     PyObject *m;
diff --git a/PC/config.c b/PC/config.c
index c96eb26..2044688 100644
--- a/PC/config.c
+++ b/PC/config.c
@@ -43,6 +43,7 @@
 #endif
 extern void init_codecs(void);
 extern void initxreadlines(void);
+extern void init_weakref(void);
 
 /* XXX tim: what's the purpose of ADDMODULE MARKER? */
 /* -- ADDMODULE MARKER 1 -- */
@@ -95,6 +96,7 @@
 
         {"_codecs", init_codecs},
 	{"xreadlines", initxreadlines},
+	{"_weakref", init_weakref},
 
 /* XXX tim: what's the purpose of ADDMODULE MARKER? */
 /* -- ADDMODULE MARKER 2 -- */
diff --git a/PCbuild/pythoncore.dsp b/PCbuild/pythoncore.dsp
index 256de83..f106828 100644
--- a/PCbuild/pythoncore.dsp
+++ b/PCbuild/pythoncore.dsp
@@ -195,6 +195,21 @@
 # End Source File
 # Begin Source File
 
+SOURCE=..\Modules\_weakref.c
+
+!IF  "$(CFG)" == "pythoncore - Win32 Release"
+
+!ELSEIF  "$(CFG)" == "pythoncore - Win32 Debug"
+
+!ELSEIF  "$(CFG)" == "pythoncore - Win32 Alpha Debug"
+
+!ELSEIF  "$(CFG)" == "pythoncore - Win32 Alpha Release"
+
+!ENDIF 
+
+# End Source File
+# Begin Source File
+
 SOURCE=..\Objects\abstract.c
 
 !IF  "$(CFG)" == "pythoncore - Win32 Release"