Blender Git Loki

Cycles: Allow early outputs from the integrator initialization

The was never an early output happening in this kernel, so the issue
was never detected yet.

Need to keep path and shadow path next kernels initialized to 0 in
this case, otherwise the kernel scheduling will not terminate the
path. Using path termination call is not possible in its current
implementation by the looks of it, because there is no previous
kernel scheduled yet.

Solved by splitting the state initialization into two parts, allowing
an early output prior to the full initialization or even prior to the
ray initialization.

The thing which is good in this approach is that it also initializes
buffer access in the state, so that the adaptive sampling can access
it in the general manner to perform early output checks.