Roto-till and clean up libblkid API.

Roto-till and clean up libblkid API.

read.c (parse_tag): Do not return that blkid_tag when parsing
	the blkid.tag file.

resolve.c (blkid_get_token, blkid_get_tagname_devname): Fold in
	code from removed functions

tag.c (blkid_create_tag): Don't return the newly tag strcture
	any more, as it's not needed.
	(blkid_find_tag_cache, blkid_get_tag_cache,
	 blkid_token_to_tag, blkid_find_tv_tags): Remove these
	functions, as they are either only used once or have
	interfaces that should be deprecated.
	(blkid_find_tag_dev, blkid_find_head_cache): Replace use
	of blkid_tag with one or two const char * type/value
	arguments.
	(blkid_find_dev_with_tag): Fold in code from removed functions

probe.h, probe.c: Use a more sophisticated set of byte-swapping
	routines which are more compact and efficient.  Drop
	calculation of bid_free, since it's unnecessary.  Avoid

save.c (blkid_save_cache): Set the permissions on the blkid
	cache file to 644.