remove initializing constructors from "dumb structs"

As suggested by Marc Zinnschlag:
https://github.com/OpenMW/openmw/pull/423#issuecomment-68526701

components/esm/loadcell.hpp

@@ -70,23 +70,17 @@ struct Cell
   {
     int mFlags;
     int mX, mY;
-
-    DATAstruct() : mFlags(0), mX(0), mY(0) {}
   };
 
   struct AMBIstruct
   {
     Color mAmbient, mSunlight, mFog;
     float mFogDensity;
-
-    AMBIstruct() : mAmbient(0), mSunlight(0), mFog(0), mFogDensity(0) {}
   };
 
   Cell() : mWater(0),
            mName(""),
            mRegion(""),
-           mData(DATAstruct()),
-           mAmbi(AMBIstruct()),
            mWaterInt(false),
            mMapColor(0),
            mRefNumCounter(0)