build: remove double LIBBITCOIN_SERVER from bench-Makefile

Author: brakmic

src/Makefile.bench.include

@@ -48,7 +48,6 @@ bench_bench_bitcoin_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 bench_bench_bitcoin_LDADD = \
   $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_WALLET) \
-  $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_COMMON) \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_CONSENSUS) \