change the cfdataref typedef to be more flexible/correct
diff --git a/src/cryptography/hazmat/bindings/commoncrypto/cf.py b/src/cryptography/hazmat/bindings/commoncrypto/cf.py
index 6a6dbc4..77d2d7c 100644
--- a/src/cryptography/hazmat/bindings/commoncrypto/cf.py
+++ b/src/cryptography/hazmat/bindings/commoncrypto/cf.py
@@ -16,7 +16,7 @@
typedef const void * CFAllocatorRef;
const CFAllocatorRef kCFAllocatorDefault;
-typedef const void * CFDataRef;
+typedef ... *CFDataRef;
typedef signed long long CFIndex;
typedef ... *CFStringRef;
typedef ... *CFArrayRef;