gnu: mpfr: Skip failing test on the Hurd.

* gnu/packages/multiprecision.scm (mpfr)[arguments]: When building natively on
the Hurd, add 'skip-tests' phase to skip "tsprintf".

gnu/packages/multiprecision.scm

@@ -9,6 +9,7 @@
 ;;; Copyright © 2018, 2019, 2021, 2023 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2021 Vinicius Monego <monego@posteo.net>
 ;;; Copyright © 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com>
+;;; Copyright © 2023 Janneke Nieuwenhuizen <janneke@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -126,6 +127,17 @@ (define-public mpfr
                                 ".tar.xz"))
             (sha256 (base32
                      "14yr4sf4mys64nzbgnd997l6l4n8l9vsjnnvnb0lh4jh2ggpi8q6"))))
+   (arguments
+    (list
+     #:phases (if (system-hurd?)
+                  #~(modify-phases %standard-phases
+                      (add-after 'unpack 'skip-tests
+                        (lambda _
+                          (substitute*
+                              "tests/tsprintf.c"
+                            (("(^| )main *\\(.*" all)
+                             (string-append all "{\n  exit (77);//"))))))
+                  #~%standard-phases)))
    (build-system gnu-build-system)
    (outputs '("out" "debug"))
    (propagated-inputs (list gmp))            ; <mpfr.h> refers to <gmp.h>