Make one of the new tests fail correctly on pre-C++17 systems

llvm-svn: 286872
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 10e59fac3ed6bf7b24eb59548416b67cff330b31
1 file changed