 Handle MSVC's definition of __cplusplus
 Handle MSVC's definition of __cplusplus

MSVC doesnt define __cplusplus correctly unless a compiler flag is passed (/Zc:__cplusplus) but _MSVC_LANG is defined correctly.
To avoid users needing to pass an extra compile flag, I suggest we handle it in the cpp_dialect.h file

jaredhoberock/thrust,jaredhoberock/thrust,thrust/thrust,thrust/thrust,thrust/thrust,thrust/thrust,jaredhoberock/thrust,jaredhoberock/thrust,andrewcorrigan/thrust-multi-permutation-iterator,andrewcorrigan/thrust-multi-permutation-iterator,andrewcorrigan/thrust-multi-permutation-iterator,jaredhoberock/thrust,thrust/thrust