Robert Maynard authored Sep 26, 2017 and Brad King committed Sep 26, 2017

Starting in CUDA 9 the default compilation mode is C++14, and you need
to explicitly enable C++98/03 mode.

While at it, document `14` among the values for `CUDA_STANDARD`.  This
was accidentally left out of commit v3.9.0-rc1~118^2 (CUDA: Add support
for the C++14 standard flag, 2017-05-11).