Don't override HAVE_TR1_TYPE_TRAITS detected by configure with HAVE_TYPE_TRAITS detected by clang __has_include() as the latter is less reliable and can return true even when the header is not actually usable, as it happens with g++ 4.8 <type_traits> in non C++11 mode. Closes #15915. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75985 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775