bench: drop leftover boost::lexical_cast benches, drop header from …

…list

`boost::lexical_cast` isn't used anywhere in Dash Core, the sole remaining
use being in a benchmark, despite it no longer being used in Dash Core.
Let's drop the benchmark and drop `boost/lexical_cast.hpp` from allowed
Boost headers

src/bench/string_cast.cpp

@@ -7,7 +7,6 @@
 #include <util/strencodings.h>
 #include <util/string.h>
 
-#include <boost/lexical_cast.hpp>
 #include <string>
 
 template <typename T>
@@ -25,21 +24,6 @@ static void int_atoi(benchmark::Bench& bench)
     });
 }
 
-static void int_lexical_cast(benchmark::Bench& bench)
-{
-    bench.run([&] {
-        boost::lexical_cast<int>("1");
-    });
-}
-
-static void strings_1_lexical_cast(benchmark::Bench& bench)
-{
-    int i{0};
-    bench.run([&] {
-        boost::lexical_cast<std::string>(++i);
-    });
-}
-
 static void strings_1_numberToString(benchmark::Bench& bench)
 {
     int i{0};
@@ -56,19 +40,6 @@ static void strings_1_tostring(benchmark::Bench& bench)
     });
 }
 
-static void strings_2_multi_lexical_cast(benchmark::Bench& bench)
-{
-    int i{0};
-    bench.run([&] { static_cast<void>(
-        boost::lexical_cast<std::string>(i) +
-        boost::lexical_cast<std::string>(i+1) +
-        boost::lexical_cast<std::string>(i+2) +
-        boost::lexical_cast<std::string>(i+3) +
-        boost::lexical_cast<std::string>(i+4));
-        ++i;
-    });
-}
-
 static void strings_2_multi_numberToString(benchmark::Bench& bench)
 {
     int i{0};
@@ -97,11 +68,8 @@ static void strings_2_strptintf(benchmark::Bench& bench)
 }
 
 BENCHMARK(int_atoi);
-BENCHMARK(int_lexical_cast);
-BENCHMARK(strings_1_lexical_cast);
 BENCHMARK(strings_1_numberToString);
 BENCHMARK(strings_1_tostring);
-BENCHMARK(strings_2_multi_lexical_cast);
 BENCHMARK(strings_2_multi_numberToString);
 BENCHMARK(strings_2_multi_tostring);
 BENCHMARK(strings_2_strptintf);

test/lint/lint-includes.sh

@@ -53,7 +53,6 @@ EXPECTED_BOOST_INCLUDES=(
     boost/filesystem.hpp
     boost/filesystem/fstream.hpp
     boost/function.hpp
-    boost/lexical_cast.hpp
     boost/multi_index/hashed_index.hpp
     boost/multi_index/ordered_index.hpp
     boost/multi_index/sequenced_index.hpp