UNITY_DECLARE_TEX2DARRAY(name)
UNITY_SAMPLE_TEX2DARRAY(name,coord) // coord is float3
On DX11-like systems (DX11, and I'd assume XB1/PS4) the macros expand to:
#define UNITY_DECLARE_TEX2DARRAY(name) Texture2DArray(name); SamplerState sampler##name
#define UNITY_SAMPLE_TEX2DARRAY(name,coord) name.Sample(coord)