fix gcc4 error:
onexit.c:10: error: static declaration of '__atexit_list' follows non-static declaration
atexit.h:16: error: previous declaration of '__atexit_list' was here

diff --git a/klibc/atexit.h b/klibc/atexit.h
index a60d641..792141d 100644
--- a/klibc/atexit.h
+++ b/klibc/atexit.h
@@ -13,7 +13,5 @@
   struct atexit *next;
 };
 
-extern struct atexit *__atexit_list;
-
 #endif /* ATEXIT_H */