Define front- and back-facing polygons, gc_CCW by default

Property definitions

glesv2 :: glesv2 $ Sys :: glFrontFace
# Define front- and back-facing polygons, `gc_CCW` by default
fun glFrontFace(mode: GLFrontFaceMode) `{ glFrontFace(mode); `}
lib/glesv2/glesv2.nit:1242,1--1243,63