clusterizer: Fix attributes of meshopt_buildMeshletsFlex

This function is intended to be tagged as "experimental" per comment:
interface and the particular behavior of some parameters is subject to
change.

Author: zeux

src/meshoptimizer.h

@@ -565,7 +565,7 @@ MESHOPTIMIZER_API size_t meshopt_buildMeshletsBound(size_t index_count, size_t m
  * cone_weight should be set to 0 when cone culling is not used, and a value between 0 and 1 otherwise to balance between cluster size and cone culling efficiency; additionally, cone_weight can be set to a negative value to prioritize axis aligned clusters (for raytracing) instead
  * split_factor should be set to a non-negative value; when greater than 0, clusters that have large bounds may be split unless they are under the min_triangles threshold
  */
-MESHOPTIMIZER_API size_t meshopt_buildMeshletsFlex(struct meshopt_Meshlet* meshlets, unsigned int* meshlet_vertices, unsigned char* meshlet_triangles, const unsigned int* indices, size_t index_count, const float* vertex_positions, size_t vertex_count, size_t vertex_positions_stride, size_t max_vertices, size_t min_triangles, size_t max_triangles, float cone_weight, float split_factor);
+MESHOPTIMIZER_EXPERIMENTAL size_t meshopt_buildMeshletsFlex(struct meshopt_Meshlet* meshlets, unsigned int* meshlet_vertices, unsigned char* meshlet_triangles, const unsigned int* indices, size_t index_count, const float* vertex_positions, size_t vertex_count, size_t vertex_positions_stride, size_t max_vertices, size_t min_triangles, size_t max_triangles, float cone_weight, float split_factor);
 
 /**
  * Meshlet optimizer