generator: fix import on Windows
generator: fix import on Windows

hrehfeld/glad,valeriog-crytek/glad,bsmr-opengl/glad,aaronmjacobs/glad,dbralir/glad,dbralir/glad,QUSpilPrgm/glad,QUSpilPrgm/glad,bsmr-opengl/glad,0x1100/glad,hrehfeld/glad,aaronmjacobs/glad,bsmr-opengl/glad,0x1100/glad,hrehfeld/glad,QUSpilPrgm/glad,dbralir/glad,0x1100/glad,0x1100/glad,valeriog-crytek/glad,valeriog-crytek/glad,dbralir/glad,bsmr-opengl/glad,QUSpilPrgm/glad,aaronmjacobs/glad,aaronmjacobs/glad,valeriog-crytek/glad,hrehfeld/glad