examples/librados: fix bufferlist::copy() in hello_world.cc.

Signed-off-by: Radoslaw Zarzynski <[email protected]>

examples/librados/hello_world.cc

@@ -169,7 +169,7 @@ int main(int argc, const char **argv)
     std::cout << "we read our object " << object_name
               << ", and got back " << ret << " bytes with contents\n";
     std::string read_string;
-    read_buf.copy(0, ret, read_string);
+    read_buf.begin().copy(ret, read_string);
     std::cout << read_string << std::endl;
   }