修复编译错误：
gcc：4.8.5 20150623
linux：3.10.0-327.el7.x86_64
centos7
错误详情：
/root/code/muduo-master/muduo/base/tests/Thread_bench.cc:83:22: error: declaration of ‘start’ shadows a member of 'this' [-Werror=shadow]
muduo::Timestamp start = muduo::Timestamp::now();
^
/root/code/muduo-master/muduo/base/tests/Thread_bench.cc: In member function ‘void Bench::stop()’:
/root/code/muduo-master/muduo/base/tests/Thread_bench.cc:107:22: error: declaration of ‘stop’ shadows a member of 'this' [-Werror=shadow]
muduo::Timestamp stop = muduo::Timestamp::now();
^
cc1plus: all warnings being treated as errors
修复编译错误： gcc：4.8.5 20150623 linux：3.10.0-327.el7.x86_64 centos7 错误详情： /root/code/muduo-master/muduo/base/tests/Thread_bench.cc:83:22: error: declaration of ‘start’ shadows a member of 'this' [-Werror=shadow] muduo::Timestamp start = muduo::Timestamp::now(); ^ /root/code/muduo-master/muduo/base/tests/Thread_bench.cc: In member function ‘void Bench::stop()’: /root/code/muduo-master/muduo/base/tests/Thread_bench.cc:107:22: error: declaration of ‘stop’ shadows a member of 'this' [-Werror=shadow] muduo::Timestamp stop = muduo::Timestamp::now(); ^ cc1plus: all warnings being treated as errors