More minor regex cleanup

More minor regex cleanup

Problems reported by Mattias Engdegård in:
https://lists.gnu.org/r/emacs-devel/2019-03/msg00643.html
plus a few others that I noticed.
* lisp/auth-source-pass.el (auth-source-pass--parse-data):
* lisp/org/org-datetree.el (org-datetree--find-create):
* lisp/org/org-pcomplete.el (org-thing-at-point):
* lisp/progmodes/js.el (js--end-of-do-while-loop-p):
* lisp/textmodes/sgml-mode.el:
(sgml-electric-tag-pair-before-change-function):
* lisp/textmodes/texnfo-upd.el (texinfo-menu-copy-old-description):
* lisp/url/url-http.el (url-http-parse-response):
Fix regular expression and similar syntax.