Replace forEach with Count

Use count where you do not need _forEachIndex variable, it's quicker
than forEach.

SQF/dayz_code/actions/show_dialog.sqf

@@ -18,7 +18,7 @@ TraderCatList = [];
 	private ["_index", "_x"];
 	_index = lbAdd [TraderDialogCatList, _x select 0];
 	TraderCatList set [count TraderCatList, _x select 1];
-} forEach _trader_data;
+} count _trader_data;
 waitUntil { !dialog };
 TraderCurrentCatIndex = -1;
 TraderCatList = -1;