Replace manually crafted hex regexes with [:xdigit:]

Replace manually crafted hex regexes with [:xdigit:]

* admin/charsets/mapconv:
* build-aux/gitlog-to-changelog (parse_amend_file, git_dir_option):
* lisp/progmodes/verilog-mode.el (verilog-delay-re):
(verilog-type-font-keywords, verilog-read-always-signals-recurse):
(verilog-is-number):
* lisp/progmodes/vera-mode.el (vera-font-lock-keywords):
* test/src/emacs-module-tests.el (mod-test-sum-test):
* lisp/xml.el: (xml--entity-replacement-text):
* lisp/version.el (emacs-repository-version-git):
* lisp/textmodes/sgml-mode.el (sgml-quote):
* lisp/textmodes/css-mode.el (css-escapes-re)
(css--colors-regexp):
* lisp/progmodes/prolog.el (prolog-syntax-propertize-function):
* lisp/progmodes/hideif.el (hif-token-regexp, hif-tokenize):
* lisp/progmodes/ebnf-dtd.el: (ebnf-dtd-attlistdecl)
(ebnf-dtd-entitydecl, ebnf-dtd-lex):
* lisp/progmodes/ebnf-ebx.el (ebnf-ebx-hex-character):
* lisp/progmodes/ebnf-abn.el (ebnf-abn-character):
* lisp/progmodes/cperl-mode.el (cperl-highlight-charclass)
(cperl-find-pods-heres):
* lisp/progmodes/cc-mode.el (c-maybe-quoted-number-head)
(c-maybe-quoted-number, c-parse-quotes-before-change)
(c-parse-quotes-after-change, c-quoted-number-head-before-point)
(c-quoted-number-straddling-point):
* lisp/progmodes/ada-mode.el (featurep, ada-in-numeric-literal-p)
(ada-font-lock-keywords):
* lisp/org/org-mobile.el (org-mobile-copy-agenda-files)
* lisp/org/org-table.el (org-table-number-regexp):
(org-mobile-update-checksum-for-capture-file):
* lisp/nxml/xsd-regexp.el (xsdre-gen-categories):
* lisp/nxml/xmltok.el (let*):
* lisp/nxml/rng-xsd.el (rng-xsd-convert-hex-binary)
(rng-xsd-convert-any-uri):
* lisp/nxml/rng-uri.el (rng-uri-file-name-1)
(rng-uri-unescape-multibyte, rng-uri-unescape-unibyte)
(rng-uri-unescape-unibyte-match)
(rng-uri-unescape-unibyte-replace):
* lisp/nxml/rng-cmpct.el (rng-c-process-escapes):
* lisp/nxml/nxml-maint.el (nxml-insert-target-repertoire-glyph-set):
* lisp/net/shr-color.el (shr-color->hexadecimal):
* lisp/mail/rfc2231.el (rfc2231-decode-encoded-string):
* lisp/international/mule-cmds.el (read-char-by-name):
* lisp/htmlfontify.el (hfy-hex-regex):
* lisp/gnus/nneething.el (nneething-decode-file-name):
* lisp/gnus/mml-sec.el (mml-secure-find-usable-keys):
* lisp/gnus/gnus-art.el (gnus-button-mid-or-mail-heuristic-alist):
* lisp/faces.el (read-color):
* lisp/epg.el (epg--status-ERRSIG, epg--status-VALIDSIG)
(epg--status-SIG_CREATED, epg--decode-percent-escape)
(epg--decode-hexstring, epg--decode-quotedstring)
(epg-dn-from-string):
* lisp/emulation/cua-rect.el (cua-incr-rectangle):
* lisp/dnd.el (dnd-unescape-uri):
* lisp/cedet/semantic/lex.el (semantic-lex-number-expression):
* lisp/cedet/semantic/java.el (semantic-java-number-regexp):
* lisp/calc/calc-lang.el (pascal):
* lisp/calc/calc-ext.el (math-read-number-fancy):
* lisp/calc/calc-aent.el (math-read-token):
Replace various combinations of [0-9a-fA-F] with [[:xdigit:]].
(Bug#36167)