Add tag support. Error for dangling qualifying predicates.

Add tag support.  Error for dangling qualifying predicates.
	* config/tc-ia64.c (struct md): New field tag_fixups.
	(ia64_flush_insns): Handle tag_fixups.  Error if dangling
	qualifying predicate.
	(emit_one_bundle): Delete spurious multiplication by one.  Handle
	tag_fixups.
	(ia64_start_line): Error if dangling qualifying predicate.
	(defining_tag): New static variable.
	(ia64_unrecognized_line, case '['): Parse tags.
	(ia64_frob_label): Create tag_fixups.
	(md_assemble): Reset md.qp.X_op after using it.