Something more serious seems to be up with guix staging because I get,
on trying "make" (after "./configure --localstatedir=/var") inside guix staging
(commit df09e1d6e71f68a8fb44bcc9f13e625f9f9701a5) on x86_64:

Backtrace:
In ice-9/boot-9.scm:
   222:29 19 (map1 _)
   222:29 18 (map1 _)
   222:29 17 (map1 _)
   222:29 16 (map1 _)
   222:29 15 (map1 _)
   222:29 14 (map1 _)
   222:29 13 (map1 (((gnu services base)) ((gnu bootloader)) ((…)) …))
   222:29 12 (map1 (((gnu bootloader)) ((gnu system shadow)) ((…)) …))
   222:29 11 (map1 (((gnu system shadow)) ((gnu system nss)) ((…)) …))
   222:29 10 (map1 (((gnu system nss)) ((gnu system locale)) ((…)) …))
   222:17  9 (map1 (((gnu system locale)) ((gnu system pam)) ((…)) …))
  2800:17  8 (resolve-interface (gnu system locale) #:select _ #:hide …)
In ice-9/threads.scm:
    390:8  7 (_ _)
In ice-9/boot-9.scm:
  2726:13  6 (_)
In ice-9/threads.scm:
    390:8  5 (_ _)
In ice-9/boot-9.scm:
  2994:20  4 (_)
   2312:4  3 (save-module-excursion #<procedure 44e0a50 at ice-9/boo…>)
  3014:26  2 (_)
In unknown file:
           1 (primitive-load-path "gnu/system/locale" #<procedure 20…>)
In gnu/system/locale.scm:
    124:0  0 (_)

gnu/system/locale.scm:124:0: In procedure private-lookup: No variable bound to glibc-for-target in module (gnu packages base)