[libcxx][fixup] Mark std::basic_istream::getline tests as failing for previous libcxx versions.

r318862 added a fix for 0-termination input array in case of an error. Previous
libcxx versions don't have the fix and corresponding tests should be failing.

llvm-svn: 318863
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 374cff69e0c54989e8e8a7426b74b0b248c4885d
2 files changed