this patch seems to fix some builtin-related declaration problems for me

Cython/Compiler/CythonScope.py

@@ -13,7 +13,7 @@ class CythonScope(ModuleScope):
         self.shape_entry = self.declare_cfunction('shape',
                                                   shape_func_type,
                                                   pos=None,
-                                                  visibility='public',
+                                                  visibility='extern',
                                                   cname='<error>')
 
 def create_cython_scope(context):

Cython/Compiler/Symtab.py

@@ -686,7 +686,7 @@ class BuiltinScope(Scope):
         # If python_equiv == "*", the Python equivalent has the same name
         # as the entry, otherwise it has the name specified by python_equiv.
         name = EncodedString(name)
-        entry = self.declare_cfunction(name, type, None, cname)
+        entry = self.declare_cfunction(name, type, None, cname, visibility='extern')
         entry.utility_code = utility_code
         if python_equiv:
             if python_equiv == "*":