graphics/pcl-pointclouds: unbreak with boost 1.67

In file included from /wrkdirs/usr/ports/graphics/pcl-pointclouds/work/pcl-pcl-1.8.1/outofcore/tools/outofcore_process.cpp:53:
In file included from /wrkdirs/usr/ports/graphics/pcl-pointclouds/work/pcl-pcl-1.8.1/outofcore/include/pcl/outofcore/outofcore_impl.h:50:
/wrkdirs/usr/ports/graphics/pcl-pointclouds/work/pcl-pcl-1.8.1/outofcore/include/pcl/outofcore/impl/octree_disk_container.hpp:77:74: error: no matching constructor for initialization of 'boost::uuids::random_generator' (aka 'boost::uuids::random_generator_pure')

boost::uuids::random_generator OutofcoreOctreeDiskContainer<PointT>::uuid_gen_ (&rand_gen_);
                                                                     ^          ~~~~~~~~~~

/usr/local/include/boost/uuid/random_generator.hpp:149:7: note: candidate constructor (the implicit copy constructor) not viable: no known conversion from 'boost::mt19937 *' (aka 'mersenne_twister_engine<unsigned int, 32, 624, 397, 31, 2567483615U, 11, 4294967295U, 7, 2636928640U, 15, 4022730752U, 18, 1812433253> *') to 'const boost::uuids::random_generator_pure' for 1st argument
class random_generator_pure

^

/usr/local/include/boost/uuid/random_generator.hpp:149:7: note: candidate constructor (the implicit default constructor) not viable: requires 0 arguments, but 1 was provided

PR: 227427
Reported by: antoine (via exp-run)
Obtained from: Homebrew