Removed close() from sink to have RAII semantics

example/bench.cpp

@@ -112,7 +112,6 @@ void bench(int howmany, std::shared_ptr<spdlog::logger> log)
     auto delta = system_clock::now() - start;
     auto delta_d = duration_cast<duration<double>> (delta).count();
     cout << format(int(howmany / delta_d)) << "/sec" << endl;
-    log->close();
 }
 
 
@@ -146,6 +145,5 @@ void bench_mt(int howmany, std::shared_ptr<spdlog::logger> log, int thread_count
     auto delta = system_clock::now() - start;
     auto delta_d = duration_cast<duration<double>> (delta).count();
     cout << format(int(howmany / delta_d)) << "/sec" << endl;
-    log->close();
 }