Fixes <http://bugs.gnu.org/22607>.
Reported by myglc2 <myglc2@gmail.com>.
Remove possibilities to install/delete packages to/from a system profile
both for "Package List" and "Package Info" buffers.
* emacs/guix-profiles.el (guix-system-profile-regexp): New variable.
(guix-system-profile?): New procedure.
* emacs/guix-ui-package.el (guix-package-info-insert-output): Do not
display "Install"/"Delete" button for a system profile.
(guix-package-assert-non-system-profile): New procedure.
(guix-package-execute-actions): Use it.
* emacs/guix-config.el.in (guix-emacs-interface-directory,
guix-state-directory): Rename to ...
(guix-config-emacs-interface-directory, guix-config-state-directory):
...this.
(guix-config-guile-program): New constant.
(guix-guile-program): Move to ...
* emacs/guix-external.el (guix-guile-program): ...here. Make it a
'defcustom'.
* emacs/guix-profiles.el (guix-default-profile): Use
'guix-config-state-directory'.
* emacs/guix-backend.el (guix-load-path): Use
'guix-config-emacs-interface-directory'.
* emacs/guix-{init,profiles}.el.in: Rename to ...
* emacs/guix-{init,profiles}.el: ... these. New files.
Use 'guix-config'.
* emacs/guix-config.el.in: New file.
* emacs.am (nodist_lisp_DATA): Add it. Move them to ...
(ELFILES): ... here.
* .gitignore, configure.ac: Adjust accordingly.
