cogl-texture-2d: Fix the coordinate wrapping for negative coordinates
cogl-texture-2d: Fix the coordinate wrapping for negative coordinates

The formula to wrap the coordinates to the [0,1] range was broken when
the coordinates were negative.

djdeath/cogl-android,Distrotech/cogl,djdeath/cogl-android,djdeath/cogl,gcampax/cogl,spatulasnout/cogl,gcampax/cogl,djdeath/cogl-android,spatulasnout/cogl,djdeath/cogl,collects/cogl,Distrotech/cogl,Distrotech/cogl,collects/cogl,djdeath/cogl,Distrotech/cogl,gcampax/cogl,gcampax/cogl