Fix bug 19740; round-tripping a pointer through a stream doesn't work

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@209305 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 854ad932c8926b373d1dab71b440ac79e3293c4c)
2 files changed