gnu: aspell: Truly honor $ASPELL_DICT_DIR.

Fixes <https://bugs.gnu.org/29686>.
Reported by Oleg Pykhalov <go.wigust@gmail.com>.

* gnu/packages/aspell.scm (aspell)[arguments]: Remove 'wrap-aspell' phase.
* gnu/packages/patches/aspell-default-dict-dir.patch: Add hunk to expand
the right-hand size of '|' in values like "<$FOO|$BAR/baz>".  Change
DICT_DIR to refer to "$HOME" on the right-hand side.

gnu/packages/aspell.scm

@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013, 2014, 2015, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013, 2014, 2015, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2015, 2016 Alex Kost <alezost@gmail.com>
 ;;; Copyright © 2016 John Darrington <jmd@gnu.org>
 ;;; Copyright © 2016, 2017, 2019 Efraim Flashner <efraim@flashner.co.il>
@@ -65,14 +65,6 @@
                  (("\"filter-path(.*)DICT_DIR" _ middle)
                   (string-append "\"filter-path" middle
                                  "\"" libdir "\"")))
-               #t)))
-         (add-after 'install 'wrap-aspell
-           (lambda* (#:key outputs #:allow-other-keys)
-             (let ((bin/aspell (string-append (assoc-ref outputs "out")
-                                              "/bin/aspell")))
-               (wrap-program bin/aspell
-                 '("ASPELL_CONF" "" =
-                   ("${ASPELL_CONF:-\"dict-dir ${GUIX_PROFILE:-$HOME/.guix-profile}/lib/aspell\"}")))
                #t))))))
     (inputs `(("perl" ,perl)))