Summary:
`ConstexprTestTypes::NoCtors` is an aggregate type (and consequently a literal type) in C++17,
but not in C++14 since it has a base class. This patch updates the comment to accurately describe the reason for the XFAIL.
Reviewers: EricWF
Reviewed By: EricWF
Differential Revision: https://reviews.llvm.org/D30481
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@296558 91177308-0d34-0410-b5e6-96231b3b80d8
