Fix VC12 warning "empty but controlled statement found".

code/ColladaParser.cpp

@@ -1950,9 +1950,11 @@ void ColladaParser::ReadIndexData( Mesh* pMesh)
 		}
 	}
 
-	// small sanity check
-	if (primType != Prim_TriFans && primType != Prim_TriStrips)
-		ai_assert(actualPrimitives == numPrimitives);
+#ifdef ASSIMP_BUILD_DEBUG  
+	if (primType != Prim_TriFans && primType != Prim_TriStrips) {
+		ai_assert(actualPrimitives == numPrimitives)
+	}
+#endif
 
 	// only when we're done reading all <p> tags (and thus know the final vertex count) can we commit the submesh
 	subgroup.mNumFaces = actualPrimitives;