Remove CDataStream::Init in favor of C++11 member initialization

src/bench/prevector.cpp

@@ -84,7 +84,7 @@ static void PrevectorDeserialize(benchmark::Bench& bench)
         for (auto x = 0; x < 1000; ++x) {
             s0 >> t1;
         }
-        s0.Init(SER_NETWORK, 0);
+        s0.Rewind();
     });
 }