cogl-context: Don't enable point sprites on GLES2
cogl-context: Don't enable point sprites on GLES2

On GLES2 there's no builtin mechanism to replace texture coordinates
with point sprite coordinates so calling glEnable(GL_POINT_SPRITE)
isn't valid. Instead the point sprite coords are implemented by using
a special builtin varying variable in GLSL.

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