Building with Boost.Array fails due to name lookup errors. These could
be fixed, but since no one has reported them and they are fairly old,
Boost.Array appears to be unused. Remove support for it.
Building with std::tr1::array fails due to missing features in
std::tr1:array relative to std::array. No one has reported this either,
so remove support for std::tr1:array.
Move the test for std::array into the Cxx11RequiredFeature list so that
it is run as part of the group test, rather than as a separate
statement.
