Fix typos

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@208869 91177308-0d34-0410-b5e6-96231b3b80d8
Fix typo 'fourty' in tests

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@208870 91177308-0d34-0410-b5e6-96231b3b80d8