fixed build with MinGW (#899)
fixed build with MinGW (#899)


microsoft/LightGBM,olofer/LightGBM,wxchan/LightGBM,microsoft/LightGBM,microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,Allardvm/LightGBM,Laurae2/LightGBM,henry0312/LightGBM,Laurae2/LightGBM,olofer/LightGBM,Allardvm/LightGBM,wxchan/LightGBM,Allardvm/LightGBM,wxchan/LightGBM,olofer/LightGBM,Allardvm/LightGBM,Laurae2/LightGBM,olofer/LightGBM,Laurae2/LightGBM,henry0312/LightGBM,wxchan/LightGBM,Allardvm/LightGBM,olofer/LightGBM,Laurae2/LightGBM,henry0312/LightGBM,wxchan/LightGBM,microsoft/LightGBM