disable clangs unused-local-typedef warnings
this stops clang from throwing hundreds of warnings like this:
/home/lackhove/code/nektar/library/LibUtilities/LinearAlgebra/NekPoint.hpp:244:17: warning: unused typedef 'boost_static_assert_typedef_244' [-Wunused-local-typedef]
BOOST_STATIC_ASSERT(dim::Value >= 2);
^
/usr/include/boost/static_assert.hpp:170:16: note: expanded from macro 'BOOST_STATIC_ASSERT'
BOOST_JOIN(boost_static_assert_typedef_, __LINE__) BOOST_STATIC_ASSERT_UNUSED_ATTRIBUTE
^
/usr/include/boost/config/suffix.hpp:608:28: note: expanded from macro 'BOOST_JOIN'
#define BOOST_JOIN( X, Y ) BOOST_DO_JOIN( X, Y )
^
/usr/include/boost/config/suffix.hpp:609:31: note: expanded from macro 'BOOST_DO_JOIN'
#define BOOST_DO_JOIN( X, Y ) BOOST_DO_JOIN2(X,Y)
^
/usr/include/boost/config/suffix.hpp:610:32: note: expanded from macro 'BOOST_DO_JOIN2'
#define BOOST_DO_JOIN2( X, Y ) X##Y
^
<scratch space>:16:1: note: expanded from here
boost_static_assert_typedef_244
^