Add default copy constructor to SystemError (#475)
Add default copy constructor to SystemError (#475)

* Add default copy constructor to SystemError
* Add FMT_DEFAULTED_COPY_CTOR macro

alabuzhev/fmt,lightslife/cppformat,lightslife/cppformat,cppformat/cppformat,cppformat/cppformat,alabuzhev/fmt,cppformat/cppformat,lightslife/cppformat,alabuzhev/fmt