[cleanup] Remove remaining check from dune_tr1_headers.m4

With GCC 4.4 or newer HAVE_INTEGRL_CONSTANT, HAVE_STD_HASH, and
HAVE_TYPE_TRAITS is always 1, no further testing necessary.
The test defines will be removed after the next Dune release.
[cleanup] Remove fall-back code for type_traits.

Maybe we can deprecate the complete header type_traits.hh.
[cleanup] Remove fall-back code for hashing.

There is more macro magic to be removed.
Merge branch 'p/gruenich/fs1425-remove-CXX11-checks'

Remove checks and fall-back code for hashing,
type_traits, and the remaining tr1 stuff.