anchor.diff:  get_os_wordsize({unix, darwin})  -> get_os_wordsize_with_uname();
   get_os_wordsize({unix, netbsd})  -> get_os_wordsize_with_uname();
   get_os_wordsize({unix, freebsd}) -> get_os_wordsize_with_uname();
  +get_os_wordsize({unix, dragonfly}) -> get_os_wordsize_with_uname();
   get_os_wordsize({unix, openbsd}) -> get_os_wordsize_with_uname();
   get_os_wordsize(_)               -> unsupported_os.
   
  
positive.code:     PortMode = case OS of
  		   {unix, darwin} -> false;
  		   {unix, freebsd} -> false;
  		   % Linux supports this.
  		   {unix, linux} -> true;
  		   {unix, openbsd} -> true;
  
negative.code: 
  %% FreeBSD: Look in /usr/include/sys/vmmeter.h for the format of struct
  %% vmmeter
  get_memory_usage({unix,OSname}) when OSname == freebsd; OSname == dragonfly ->
      PageSize  = freebsd_sysctl("vm.stats.vm.v_page_size"),
      PageCount = freebsd_sysctl("vm.stats.vm.v_page_count"),
      FreeCount = freebsd_sysctl("vm.stats.vm.v_free_count"),
  