Fix a bug in ConvexHull when indices are used
Fix a bug in ConvexHull when indices are used

`qh_pointid` contains indices into the `indices_` vector, which in turn
indices into `input_` point cloud. Line 375 already "dereferenced"
`qh_pointid` indices, such that `hull_indices_` contains indices into
the point cloud. Therefore, line 376 should not use `indices_`
anymore.

drmateo/pcl,drmateo/pcl,drmateo/pcl,drmateo/pcl,drmateo/pcl