[test.common_configuration] remove const to workaround icc/boost bug

dune/stuff/test/common_configuration.cc

@@ -125,9 +125,10 @@ struct ConfigTest : public testing::Test
   static const int count = 2;
   DefaultRNG<T> rng;
   RandomStrings key_gen;
-  // std::array is not assignable from list_of it seems
-  const boost::array<T, count> values;
-  const boost::array<std::string, count> keys;
+  // std::array is not assignable from list_of it seems. Don't make the following two arrays const (triggers boost/intel
+  // compiler bug, last tested with icpc version 14.0.3).
+  boost::array<T, count> values;
+  boost::array<std::string, count> keys;
   ConfigTest()
     : key_gen(8)
     , values(boost::assign::list_of<T>().repeat_fun(values.size() - 1, rng))