__d_internal.
* fhandler_disk_file.cc (struct __DIR_cache): Remove useless "typedef".
(d_dirname): Remove useless "struct".
(d_cachepos): Ditto.
(d_cache): Ditto.
(class __DIR_mounts): New class, implementing mount point tracking
for readdir.
(d_mounts): New macro for easy access to __DIR_mounts structure.
(fhandler_disk_file::opendir): Allocate __DIR_mounts structure and
let __d_internal element of dir point to it.
(fhandler_disk_file::readdir_helper): Add mount points in the current
directory, which don't have a real directory backing them.
Don't generate an inode number for /dev. Add comment, why.
(fhandler_disk_file::readdir): Move filling fname to an earlier point.
Check if current entry is a mount point and evaluate correct inode
number for it.
(fhandler_disk_file::readdir_9x): Ditto.
(fhandler_disk_file::rewinddir): Set all mount points in this directory
to "not found" so that they are listed again after calling rewinddir().
(fhandler_disk_file::closedir): Deallocate __DIR_mounts structure.
* path.cc (mount_info::get_mounts_here): New method to evaluate a list
of mount points in a given parent directory.
* shared_info.h (class mount_info): Declare get_mounts_here.