CXX=C:/RBuildTools/3.5/mingw_64/bin/g++ -std=c++1y
CXX11=C:/RBuildTools/3.5/mingw_64/bin/g++ -std=c++1y
CXX14=C:/RBuildTools/3.5/mingw_64/bin/g++ -std=c++1y
CXX17=C:/RBuildTools/3.5/mingw_64/bin/g++ -std=c++1y

CXXFLAGS=-O3 -Wno-unused-variable -Wno-unused-function
CXX11FLAGS=-O3 -Wno-unused-variable -Wno-unused-function
CXX14FLAGS=-O3 -Wno-unused-variable -Wno-unused-function
CXX17FLAGS=-O3 -Wno-unused-variable -Wno-unused-function