[cpp] Move string map over to use string hash directly, rather than via anon object
[cpp] Move string map over to use string hash directly, rather than via anon object

pleclech/hacking-haxe,pleclech/hacking-haxe,pleclech/hacking-haxe,pleclech/hacking-haxe,pleclech/hacking-haxe,pleclech/hacking-haxe