Forward declare some memoryview utility code functions.

Cython/Utility/Buffer.c

@@ -159,6 +159,11 @@ static void __Pyx_ReleaseBuffer(Py_buffer *view) {
 static CYTHON_INLINE int  __Pyx_GetBufferAndValidate(Py_buffer* buf, PyObject* obj,
     __Pyx_TypeInfo* dtype, int flags, int nd, int cast, __Pyx_BufFmt_StackElem* stack);
 static CYTHON_INLINE void __Pyx_SafeReleaseBuffer(Py_buffer* info);
+static const char* __Pyx_BufFmt_CheckString(__Pyx_BufFmt_Context* ctx, const char* ts);
+static void __Pyx_BufFmt_Init(__Pyx_BufFmt_Context* ctx,
+                              __Pyx_BufFmt_StackElem* stack,
+                              __Pyx_TypeInfo* type); // PROTO
+
 
 /////////////// BufferFormatCheck ///////////////
 static CYTHON_INLINE int __Pyx_IsLittleEndian(void) {