changing all references of std::auto_ptr to std::unique_ptr and changing the implementation of get_directory_contents() to use readdir, which is now reentrant, instead of readdir_r.
Signed-off-by: Andrew Ayer <agwa@andrewayer.name>
Note: old implementations or readdir might not be re-entrant, but that's OK
because git-crypt is not multi-threaded.
