gnu: libxtst: Fix cross-compiling to riscv64.

* gnu/packages/xorg.scm (libxtst)[arguments]: When cross-compiling to
riscv64, add phase to update config.{guess,sub}.
[native-inputs]: When cross-compiling to riscv64, add config.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>

gnu/packages/xorg.scm

@@ -34,6 +34,7 @@
 ;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
 ;;; Copyright © 2021 qblade <qblade@protonmail.com>
 ;;; Copyright © 2021 Lu Hui <luhux76@gmail.com>
+;;; Copyright © 2023 Zheng Junjie <873216071@qq.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -4493,13 +4494,30 @@ (define-public libxtst
             "012jpyj7xfm653a9jcfqbzxyywdmwb2b5wr1dwylx14f3f54jma6"))))
     (build-system gnu-build-system)
     (arguments
-     '(#:configure-flags '("--disable-static")))
+     `(#:configure-flags '("--disable-static")
+       ,@(if (and (target-riscv64?)
+                  (%current-target-system))
+             `(#:phases
+               (modify-phases %standard-phases
+                 (add-after 'unpack 'update-config
+                   (lambda* (#:key native-inputs inputs #:allow-other-keys)
+                     (for-each (lambda (file)
+                                 (install-file
+                                  (search-input-file
+                                   (or native-inputs inputs)
+                                   (string-append "/bin/" file)) "."))
+                               '("config.guess" "config.sub"))))))
+             '())))
     (propagated-inputs
      (list libxi xorgproto))
     (inputs
-      (list libx11))
+     (list libx11))
     (native-inputs
-      (list pkg-config))
+     (append (if (and (target-riscv64?)
+                      (%current-target-system))
+               (list config)
+               '())
+             (list pkg-config)))
     (home-page "https://www.x.org/wiki/")
     (synopsis "Xorg library for Xtest and Record extensions")
     (description