meson/win32: There is no need install OpenGL headers on win32

This is used to avoid conflict between Windows GL headers and mesa GL headers. The GL headers resident in Windows SDK are

gl.h
glaux.h
glcorearb.h
glext.h
glu.h
glxext.h
wgl.h
wglext.h

Signed-off-by: Yonggang Luo luoyonggang@gmail.com