Fix issue with 37790e099c

Cost cannot be non-integer, and rounding issues happened.

Reported by: gameboy
This was SVN commit r25245.

binaries/data/mods/public/simulation/templates/mixins/mercenary.xml

@@ -3,7 +3,7 @@
   <Cost>
     <BuildTime op="mul">0.7</BuildTime>
     <Resources>
-      <food op="mul">0.4</food>
+      <food op="mul_round">0.4</food>
       <wood>0</wood>
       <stone>0</stone>
       <!-- Metal is specified on a per-class basis in derived templates. -->
@@ -13,7 +13,7 @@
     <VisibleClasses datatype="tokens">Mercenary</VisibleClasses>
   </Identity>
   <Loot>
-    <food op="mul">0.4</food>
+    <food op="mul_round">0.4</food>
     <wood>0</wood>
     <stone>0</stone>
   </Loot>