Function gl::DrawElementsInstanced

pub unsafe fn DrawElementsInstanced(
    mode: GLenum, 
    count: GLsizei, 
    type_: GLenum, 
    indices: *const c_void, 
    instancecount: GLsizei
)

Fallbacks: DrawElementsInstancedANGLE, DrawElementsInstancedARB, DrawElementsInstancedEXT, DrawElementsInstancedNV