Fix type definitions, module init return values, and unicode/bytes conversions
diff --git a/OpenSSL/crypto/pkey.c b/OpenSSL/crypto/pkey.c
index 82b9e06..6494d2a 100644
--- a/OpenSSL/crypto/pkey.c
+++ b/OpenSSL/crypto/pkey.c
@@ -197,7 +197,7 @@
 }
 
 PyTypeObject crypto_PKey_Type = {
-    PyVarObject_HEAD_INIT(&PyType_Type, 0)
+    PyOpenSSL_HEAD_INIT(&PyType_Type, 0)
     "OpenSSL.crypto.PKey",
     sizeof(crypto_PKeyObj),
     0,