x86_64-w64-mingw32-gcc spline_given_knots4.c -I/cygdrive/c/gsl/include -L/cygdrive/c/gsl/lib -llapack -o spline_given_knots4.o -c
x86_64-w64-mingw32-gcc -shared spline_given_knots4.o -o spline_given_knots4.dll -I/cygdrive/c/gsl/include -L/cygdrive/c/gsl/lib -llapack
lRlapackを/cyg*/c/Pr*Files/R/R*/bin/x64をあたりからキャレントディレクトリにコピー
x86_64-w64-mingw32-gcc -shared spline_given_knots4.o -o spline_given_knots4.dll -L. -lRlapack
