Be more conservative about is_trivial support

`std::is_trivial` is part of the C++14 specification. However, we have
encountered multiple compilers that purport to implement C++14 but do
not implement `std::is_trivial` and the like checks correctly.

To avoid such issues, only use `std::is_trivial` on compilers that we
have tested to support it.
5 jobs for safer-is-trivial
Status Name Job ID Coverage
  External
passed cdash-buildbot

passed vtk-m-dragnipur-osx-shared-debug+32bit_ids+64bit_coords+clang+tbb

00:11:45

passed vtk-m-dragnipur-osx-static-release+64bit_coords+clang+tbb

00:16:15

passed vtk-m-osheim-windows-shared-debug+ninja-vs-2017+tbb

00:25:41

passed vtk-m-osheim-windows-static-release+ninja-vs-2017+tbb

00:28:39