[libcxx] Fix c++98 test failures.

Adds XFAIL/UNSUPPORTED lit tags as appropriate. Gets a clean test run
for -std=c++98 on Fedora 20.

NFC.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@271741 91177308-0d34-0410-b5e6-96231b3b80d8
22 files changed