optimize double anchors such as ^$

optimize double anchors such as ^$

2008-05-15  Paolo Bonzini  <bonzini@gnu.org>

	* lib/regcomp.c (optimize_utf8): Add a note on why we test
	opr.ctx_type.
	(calc_first): Initialize constraint field.
	(duplicate_node_closure): Use it instead of special casing ANCHORS.
	Fix grammar.
	(duplicate_node): Merge constraint field for all node types.
	(calc_eclosure_iter): Look at constraint field for all node types.
	* lib/regex_internal.c (create_cd_newstate): Don't look at
	opr.ctx_type.