Don't call purecopy in textmodes/*.el

Don't call purecopy in textmodes/*.el

* lisp/textmodes/bibtex.el (bibtex-url, bibtex-search-crossref):
* lisp/textmodes/fill.el (adaptive-fill-regexp)
(adaptive-fill-first-line-regexp):
* lisp/textmodes/ispell.el (ispell-menu-map)
(ispell-skip-region-alist, ispell-tex-skip-alists):
* lisp/textmodes/rst.el (auto-mode-alist):
* lisp/textmodes/texinfo.el (texinfo-open-quote):
* lisp/textmodes/tex-mode.el (tex-directory, tex-run-command)
(latex-run-command, slitex-run-command, tex-start-options)
(tex-start-commands, tex-bibtex-command, tex-dvi-print-command)
(tex-alt-dvi-print-command, tex-dvi-view-command)
(tex-show-queue-command, tex-open-quote, tex-close-quote):
* lisp/textmodes/texinfo.el (texinfo-open-quote)
(texinfo-close-quote): Remove calls to purecopy.

(cherry picked from commit e44b1bf5cca00edb87452f864e9c450116d8f830)