Fix __int128_t handling with clang-cl (#208)
Fix __int128_t handling with clang-cl (#208)

So far cpp-sort that any standard library that had __SIZEOF_INT128__
defined was either libc++ or libstdc++. However it turned out that
clang-cl provides that type but targets the Microsoft STL, so our
internal family of is_integral traits had to be updated to take that
new information into account.

Morwenn/cpp-sort,Morwenn/cpp-sort,Morwenn/cpp-sort,Morwenn/cpp-sort