Teach Windows build about the _weakref module.
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 -- */