games/criticalmass: unbreak with gcc6 or later

In file included from Config.cpp:26:0:
./Config.hpp:94:63: error: template argument 3 is invalid

hash_map< string, Value*, hash<string>, equal_to<string> > &kvmap);
                                                         ^

./Config.hpp:94:63: error: template argument 3 is invalid
./Config.hpp:94:63: error: template argument 3 is invalid
./Config.hpp:94:6: error: 'hash_map' is not a type

hash_map< string, Value*, hash<string>, equal_to<string> > &kvmap);
^~~~~~~~

./Config.hpp:94:14: error: expected ',' or '...' before '<' token

hash_map< string, Value*, hash<string>, equal_to<string> > &kvmap);
        ^

./Config.hpp:97:63: error: template argument 3 is invalid

hash_map< string, Value*, hash<string>, equal_to<string> > &kvmap);
                                                         ^

[...]