* bitmap.c (struct bitmap_descriptor): Remove forward declaration.
	(struct bitmap_head_def): Remove desc pointer.  Add descriptor_id
	field.  Reorder fields for pointer alignment.
	* bitmap.c: Include vec.h.
	(struct bitmap_descriptor): Rename to bitmap_descriptor_d.
	(bitmap_descriptor): New typedef, pointer to bitmap_descriptor_d.
	Update all struct bitmap_descriptor references.
	(next_bitmap_desc_id): New running index for bitmap desciptors.
	(bitmap_descriptors): Vec of all bitmap descriptors by descriptor id.
	(hash_descriptor, eq_descriptor): Update for struct bitmap_descriptor
	change.
	(bitmap_descriptor): Rename function to get_bitmap_descriptor.
	Stuff newly allocated bitmap descriptor into bitmap_descriptors.
	Set the bitmap descriptor id.
	(bitmap_register): Lookup bitmap desciptor and store its ID in
	the passed bitmap.
	(register_overhead): Likewise.
	(bitmap_find_bit): Lookup descriptor by id in bitmap_descriptors.
	(print_statistics): Update for struct bitmap_descriptor change.

From-SVN: r194469