Fix #32907: failure rendering a complex node setup, hitting fixed max number

of closures limit. Optimized the code now so it can handle more.

Change SVM mix/add closure handling, now we transform the node graph so that
the mix weights are fed into the closure nodes directly.

intern/cycles/render/nodes.h

@@ -351,6 +351,11 @@ public:
 	SHADER_NODE_CLASS(MixClosureNode)
 };
 
+class MixClosureWeightNode : public ShaderNode {
+public:
+	SHADER_NODE_CLASS(MixClosureWeightNode);
+};
+
 class InvertNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(InvertNode)