Update vendored LibOVR to fix build errors

I was getting the following error when trying to build

`error: no member named 'Dot' in 'OVR::Vector3<float>`

    /Users/joerick/v002-Oculus-Rift/v002 Oculus Rift/v002 Oculus Rift/LibOVR/Src/Kernel/OVR_Math.cpp:73:38: error: no member named 'Dot' in 'OVR::Vector3<float>'
        Matrix4f m(x.x,  x.y,  x.z,  -(x.Dot(eye)),
                                       ~ ^

After updating the SDK it all works again.