Generate n texture names

Property definitions

glesv2 :: glesv2 $ Sys :: glGenTextures
# Generate `n` texture names
fun glGenTextures(n: Int): Array[Int]
do
	var array = new CIntArray(n)
	native_glGenTextures(n, array.native_array)
	var a = array.to_a
	array.destroy
	return a
end
lib/glesv2/glesv2.nit:587,1--595,3