[trivial] Add end of namespace comments

src/bench/checkblock.cpp

@@ -11,7 +11,7 @@
 
 namespace block_bench {
 #include "bench/data/block413567.raw.h"
-}
+} // namespace block_bench
 
 // These are the two major time-sinks which happen after we have fully received
 // a block off the wire, but before we can relay the block on to peers using