[C++] Handle DT_UNKNOWN properly in find emulator
[C++] Handle DT_UNKNOWN properly in find emulator

When readdir returns DT_UNKNOWN, we need to check the file
type using lstat. This is necessary for some filesystems such
as sshfs.

colincross/kati,danw/kati,google/kati,shinh/kati,colincross/kati,google/kati,google/kati,shinh/kati,shinh/kati,danw/kati,danw/kati,danw/kati,colincross/kati,colincross/kati,colincross/kati,google/kati,google/kati,danw/kati,shinh/kati,danw/kati,colincross/kati,shinh/kati,shinh/kati