[R-package] remove Makefile hack in install.libs.R (#3528)
[R-package] remove Makefile hack in install.libs.R (#3528)


microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,microsoft/LightGBM,microsoft/LightGBM,henry0312/LightGBM,microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM