Remove cryptoppwin submodule (#754)

third_party/cryptoppwin/include/cryptopp/secblockfwd.h

@@ -0,0 +1,29 @@
+// secblockfwd.h - written and placed in the public domain by Jeffrey Walton
+
+/// \file secblockfwd.h
+/// \brief Forward declarations for SecBlock
+/// \details secblock.h and misc.h have a circular dependency. secblockfwd.h
+///  allows the library to sidestep the circular dependency, and reference
+///  SecBlock classes without the full implementation.
+/// \since Crypto++ 8.3
+
+#ifndef CRYPTOPP_SECBLOCKFWD_H
+#define CRYPTOPP_SECBLOCKFWD_H
+
+#include "config.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+template <class T, class A>
+class SecBlock;
+
+template <class T, bool A>
+class AllocatorWithCleanup;
+
+typedef SecBlock<byte, AllocatorWithCleanup<byte, false> > SecByteBlock;
+typedef SecBlock<word, AllocatorWithCleanup<word, false> > SecWordBlock;
+typedef SecBlock<byte, AllocatorWithCleanup<byte,  true> > AlignedSecByteBlock;
+
+NAMESPACE_END
+
+#endif  // CRYPTOPP_SECBLOCKFWD_H