guix: Install UTF-8 locale to build the site.

* guix.scm: Install UTF-8 locale.

guix.scm

@@ -25,6 +25,7 @@
 
 (use-modules (gnu) (guix)
              ((guix git-download) #:select (git-predicate))
+             (gnu packages base)
              (gnu packages guile-xyz))
 
 (define this-directory
@@ -40,6 +41,12 @@
                  #~(begin
                      (use-modules (guix build utils))
 
+                     ;; Install a Unicode-capable locale.
+                     (setenv "GUIX_LOCPATH"
+                             #$(file-append glibc-utf8-locales
+                                            "/lib/locale"))
+                     (setenv "LC_ALL" "en_US.utf8")
+
                      (copy-recursively #$source ".")
                      (invoke #$(file-append haunt "/bin/haunt") "build")
                      (copy-recursively "site" #$output))))