du: Hash with a mechanism that's simpler and takes less memory.

du: Hash with a mechanism that's simpler and takes less memory.

* gl/lib/dev-map.c, gl/lib/dev-map.h, gl/modules/dev-map: Remove.
* gl/lib/ino-map.c, gl/lib/ino-map.h, gl/modules/ino-map: New files.
* gl/modules/dev-map-tests, gl/tests/test-dev-map.c: Remove.
* gl/modules/ino-map-tests, gl/tests/test-ino-map.c: New files.
* gl/lib/di-set.h (struct di_set): Renamed from struct di_set_state,
and now private.  All uses changed.
(_ATTRIBUTE_NONNULL_): Don't assume C99.
(di_set_alloc): Renamed from di_set_init, with no size arg.
Now allocates the object rather than initializing it.
For now, this no longer takes an initial size; we can put this
back later if it is needed.
* gl/lib/di-set.c: Include hash.h, ino-map.h, and limits.h instead of
stdio.h, assert.h, stdint.h, sys/types.h (di-set.h includes that
now), sys/stat.h, and verify.h.
(N_DEV_BITS_4, N_INO_BITS_4, N_DEV_BITS_8, N_INO_BITS_8): Remove.
(struct dev_ino_4, struct dev_ino_8, struct dev_ino_full): Remove.
(enum di_mode): Remove.
(hashint): New typedef.
(HASHINT_MAX, LARGE_INO_MIN): New macros.
(struct di_ent): Now maps a dev_t to a inode set, instead of
containing a union.
(struct dev_map_ent): Remove.
(struct di_set): New type.
(is_encoded_ptr, decode_ptr, di_ent_create): Remove.
(di_ent_hash, di_ent_compare, di_ent_free, di_set_alloc, di_set_free):
(di_set_insert): Adjust to new representation.
(di_ino_hash, map_device, map_inode_number): New functions.
* gl/modules/di-set (Depends-on): Replace dev-map with ino-map.
Remove 'verify'.
* gl/tests/test-di-set.c: Adjust to the above changes to API.
* src/du.c (INITIAL_DI_SET_SIZE): Remove.
(hash_ins, main): Adjust to new di-set API.