Issue an error if config.hpp is not found.
Issue an error if config.hpp is not found.

ajjl/mlpack,theranger/mlpack,theranger/mlpack,ranjan1990/mlpack,stereomatchingkiss/mlpack,ranjan1990/mlpack,ranjan1990/mlpack,darcyliu/mlpack,theranger/mlpack,stereomatchingkiss/mlpack,darcyliu/mlpack,darcyliu/mlpack,palashahuja/mlpack,palashahuja/mlpack,ajjl/mlpack,palashahuja/mlpack,ajjl/mlpack,stereomatchingkiss/mlpack