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
Fix Bug 19678 - libc++ does not correctly handle the regex: '[^\0]*'

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@209307 91177308-0d34-0410-b5e6-96231b3b80d8