Cycles microdisplacement: move subdivision options to subsurf modifier

Subdivision options can now be found in the subsurf modifier. The modifier must
be the last in the stack or the options will be unavailable. Catmull-Clark
subdivision is still unavailable and will fallback to linear subdivision instead

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D2109

intern/cycles/render/mesh.h

@@ -119,6 +119,14 @@ public:
 		DISPLACE_NUM_METHODS,
 	};
 
+	enum SubdivisionType {
+		SUBDIVISION_NONE,
+		SUBDIVISION_LINEAR,
+		SUBDIVISION_CATMULL_CLARK,
+	};
+
+	SubdivisionType subdivision_type;
+
 	/* Mesh Data */
 	enum GeometryFlags {
 		GEOMETRY_NONE      = 0,