layout: restructure into src/ tests/ android/ scripts/ tools/

- extension/src/{port,platform,codepage} -> src/; native_render -> src/host
  (+ dxt, shaders/); libgr2 -> src/gr2; extension/third_party -> third_party
- extension/tests -> tests/port, libgr2/tests -> tests/gr2
- android-native -> android (build.sh, push-client.sh moved in)
- script -> scripts; tools/40250 -> tools/server; oracle -> tools/granny-oracle;
  perf tools -> tools/perf
- all build trees under build/ (native, release, android, port-gate)
- xrender:: CMake aliases -> mt::; port-map ledger impl paths rewritten

No code changes. ctest 15/15, port_gate macos+android PASS, port_map check 0 errors.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

third_party/cryptopp/rc6.h

@@ -0,0 +1,60 @@
+// rc6.h - originally written and placed in the public domain by Wei Dai
+
+/// \file rc6.h
+/// \brief Classes for the RC6 block cipher
+/// \since Crypto++ 3.0
+
+#ifndef CRYPTOPP_RC6_H
+#define CRYPTOPP_RC6_H
+
+#include "seckey.h"
+#include "secblock.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+/// \brief RC6 block cipher information
+/// \since Crypto++ 3.0
+struct RC6_Info : public FixedBlockSize<16>, public VariableKeyLength<16, 16, 32, 8>, public VariableRounds<20>
+{
+	CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() {return "RC6";}
+	typedef word32 RC6_WORD;
+};
+
+/// \brief RC6 block cipher
+/// \sa <a href="http://www.cryptopp.com/wiki/RC6">RC6</a>
+/// \since Crypto++ 3.0
+class RC6 : public RC6_Info, public BlockCipherDocumentation
+{
+	class CRYPTOPP_NO_VTABLE Base : public BlockCipherImpl<RC6_Info>
+	{
+	public:
+		void UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs &params);
+
+	protected:
+		unsigned int r;       // number of rounds
+		SecBlock<RC6_WORD> sTable;  // expanded key table
+	};
+
+	class CRYPTOPP_NO_VTABLE Enc : public Base
+	{
+	public:
+		void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const;
+	};
+
+	class CRYPTOPP_NO_VTABLE Dec : public Base
+	{
+	public:
+		void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const;
+	};
+
+public:
+	typedef BlockCipherFinal<ENCRYPTION, Enc> Encryption;
+	typedef BlockCipherFinal<DECRYPTION, Dec> Decryption;
+};
+
+typedef RC6::Encryption RC6Encryption;
+typedef RC6::Decryption RC6Decryption;
+
+NAMESPACE_END
+
+#endif