Linux specific dependencies
Linux specific dependencies

...compile backtrace.hpp only when OS is Linux
ajjl/mlpack,ajjl/mlpack,palashahuja/mlpack,ranjan1990/mlpack,palashahuja/mlpack,ranjan1990/mlpack,darcyliu/mlpack,ranjan1990/mlpack,palashahuja/mlpack,ajjl/mlpack,darcyliu/mlpack,darcyliu/mlpack