Add Benchmark to test input de-duplication worst case

Fix nits

replace utiltime?

src/Makefile.bench.include

@@ -18,6 +18,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/block_assemble.cpp \
   bench/checkblock.cpp \
   bench/checkqueue.cpp \
+  bench/duplicate_inputs.cpp \
   bench/examples.cpp \
   bench/rollingbloom.cpp \
   bench/crypto_hash.cpp \