Make it possible to build a no-exceptions variant of libcxx.

Fixes a small omission in libcxx that prevents libcxx being built when
-DLIBCXX_ENABLE_EXCEPTIONS=0 is specified.

This patch adds XFAILS to all those tests that are currently failing
on the new -fno-exceptions library variant. Follow-up patches will
update the tests (progressively) to cope with the new library variant.

Change-Id: I4b801bd8d8e4fe7193df9e55f39f1f393a8ba81a

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@252598 91177308-0d34-0410-b5e6-96231b3b80d8
158 files changed