Depsgraph: Cleanup, use explicit cloth modifier opcode

Avoids use of placeholder operation which also was involving some string
comparisons.

source/blender/depsgraph/intern/builder/deg_builder_nodes.cc

@@ -707,8 +707,7 @@ void DepsgraphNodeBuilder::build_cloth(Scene *scene, Object *object)
 	                                 _1,
 	                                 scene,
 	                                 object),
-	                   DEG_OPCODE_PLACEHOLDER,
-	                   "Cloth Modifier");
+	                   DEG_OPCODE_GEOMETRY_CLOTH_MODIFIER);
 }
 
 /* Shapekeys */

source/blender/depsgraph/intern/builder/deg_builder_relations.cc

@@ -1419,8 +1419,7 @@ void DepsgraphRelationBuilder::build_cloth(Scene * /*scene*/,
 {
 	OperationKey cache_key(&object->id,
 	                       DEG_NODE_TYPE_CACHE,
-	                       DEG_OPCODE_PLACEHOLDER,
-	                       "Cloth Modifier");
+	                       DEG_OPCODE_GEOMETRY_CLOTH_MODIFIER);
 	/* Cache component affects on modifier. */
 	OperationKey modifier_key(&object->id,
 	                          DEG_NODE_TYPE_GEOMETRY,

source/blender/depsgraph/intern/depsgraph_type_defines.cc

@@ -117,6 +117,7 @@ static const char *stringify_opcode(eDepsOperation_Code opcode)
 		STRINGIFY_OPCODE(RIGIDBODY_TRANSFORM_COPY);
 		/* Geometry. */
 		STRINGIFY_OPCODE(GEOMETRY_UBEREVAL);
+		STRINGIFY_OPCODE(GEOMETRY_CLOTH_MODIFIER);
 		/* Pose. */
 		STRINGIFY_OPCODE(POSE_INIT);
 		STRINGIFY_OPCODE(POSE_INIT_IK);

source/blender/depsgraph/intern/depsgraph_types.h

@@ -167,6 +167,7 @@ typedef enum eDepsOperation_Code {
 	/* Geometry. ---------------------------------------- */
 	/* Evaluate the whole geometry, including modifiers. */
 	DEG_OPCODE_GEOMETRY_UBEREVAL,
+	DEG_OPCODE_GEOMETRY_CLOTH_MODIFIER,
 
 	/* Pose. -------------------------------------------- */
 	/* Init pose, clear flags, etc. */