ox-publish: Use lexical binding

ox-publish: Use lexical binding

* lisp/ox-publish.el (org-publish-needed-p):
(org-publish-update-timestamp):
(org-publish-remove-all-timestamps):
(org-publish-get-base-files-1):
(org-publish-get-base-files):
(org-publish-get-project-from-filename):
(org-publish-attachment):
(org-publish-org-sitemap):
(org-publish):
(org-publish-all):
(org-publish-current-file):
(org-publish-collect-index):
(org-publish--collect-references):
(org-publish-cache-file-needs-publishing): Silence byte-compiler.
Replace `mapc' + `lambda' with `dolist'.