Fix building on Windows as Viking only supports GLIB 2.24 ATM.
SF Bugs#105: Fix Display of Lines (Clipping) at High Zoom Levels.

Properly address clipping of x,y pixel values,
 which can happen when points are far away from the viewport.
This typically happens when zoomed in very close e.g. <0.5 pixelfact,
 but also when a point is *very* far away from other points in a normal track.