* cedet/semantic/tag.el: Add declare-function statements for

* cedet/semantic/tag.el: Add declare-function statements for
semantic-current-tag, semantic-ctxt-current-mode,
semantic-format-tag-prototype, and semantic-find-first-tag-by-name.
Require semantic/lex.
(semantic-obtain-foreign-tag, semantic-tag-p)
(semantic-tag-alias-definition, semantic-tag-components)
(semantic-tag-components-with-overlays)
(semantic-insert-foreign-tag): Remove unnecessary autoloads.
(semantic-tag-mode): Require semantic/find.
(semantic--tag-find-parent-by-name): Require semantic/find.
(semantic--tag-find-parent-by-name): Require semantic/analyze/fcn/
(semantic--tag-unlink-cache-from-buffer)
(semantic--tag-link-cache-to-buffer): Require semantic.
(semantic-foreign-tag): Require semantic/doc.
(semantic-insert-foreign-tag-default, semantic-insert-foreign-tag):
Require semantic/format.