Comment 158 for bug 179988

Is there some conditional thing we can use to test whether cairo has this fix? That would be cleaner in some ways and messier in others I guess.

Could do something like;
=====
#ifndef have_cairo_1.6 // (or whatever the correct call is)
cairo_surface_set_fallback_resolution (surface, (x_dpi/72.0) * 300, (y_dpi/72.0) * 300);
#endif
=====

But then I guess that would then have to be changed for every version of cairo, so it's not worth it.