Fix not defined syslog_logger under windows
Check return code from std::remove.

In case removing a file (file_sink) fails, we throw spdlog_ex.
Merge pull request #11 from xaqq/master

Check return code from std::remove.
Add mingw build and run script for bench example
Merge pull request #12 from mintyc/add_mingw_bench

Add mingw build and run script for bench example. Thanks @mintyc