Use lexical-binding in a few more scattered files

Use lexical-binding in a few more scattered files

* lisp/registry.el: Use lexical-binding.
(registry-reindex): Remove unused var `values`.

* lisp/cedet/pulse.el: Use lexical-binding.

* lisp/cedet/semantic/idle.el: Use lexical-binding.
(semantic-idle-core-handler): Remove unused var `safe`.
(ede-auto-add-method): Declare var.
(define-semantic-idle-service): Use `declare`.  Remove unused var `setup`.
(pulse-flag): Declare var.

* lisp/net/ldap.el: Use lexical-binding.
(ldap-search-internal): Remove unused var `proc`.

* lisp/net/mairix.el: Use lexical-binding.
Remove redundant `:group` args.
(mairix-widget-create-query): Remove unnused var `allwidgets`.