view: build_progress_virtual_reader: implement close method

Close underlying reader.

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>

db/view/build_progress_virtual_reader.hh

@@ -182,6 +182,10 @@ class build_progress_virtual_reader {
             _end_of_stream = false;
             return _underlying.fast_forward_to(std::move(range), timeout);
         }
+
+        virtual future<> close() noexcept override {
+            return _underlying.close();
+        }
     };
 
 public: