fsck: remove the unused BAD_TAG_OBJECT

2175a0c (fsck: stop checking tag->tagged, 2019-10-18) stopped
checking the tagged object referred to by a tag object, which is what the
error message BAD_TAG_OBJECT was for. Since then the BAD_TAG_OBJECT
message is no longer used anywhere.

Remove the BAD_TAG_OBJECT msg-id.

Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: john-cai

fsck.h

@@ -24,7 +24,6 @@ enum fsck_msg_type {
 	FUNC(BAD_NAME, ERROR) \
 	FUNC(BAD_OBJECT_SHA1, ERROR) \
 	FUNC(BAD_PARENT_SHA1, ERROR) \
-	FUNC(BAD_TAG_OBJECT, ERROR) \
 	FUNC(BAD_TIMEZONE, ERROR) \
 	FUNC(BAD_TREE, ERROR) \
 	FUNC(BAD_TREE_SHA1, ERROR) \