Fix type definitions, module init return values, and unicode/bytes conversions
diff --git a/OpenSSL/crypto/x509ext.c b/OpenSSL/crypto/x509ext.c
index 995a079..28e8805 100644
--- a/OpenSSL/crypto/x509ext.c
+++ b/OpenSSL/crypto/x509ext.c
@@ -240,7 +240,7 @@
 }
 
 PyTypeObject crypto_X509Extension_Type = {
-    PyVarObject_HEAD_INIT(&PyType_Type, 0)
+    PyOpenSSL_HEAD_INIT(&PyType_Type, 0)
     "X509Extension",
     sizeof(crypto_X509ExtensionObj),
     0,