gnu: coreutils: Patch broken Gnulib tests.

Fixes <https://bugs.gnu.org/49459>.

* gnu/packages/patches/coreutils-gnulib-tests.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/base.scm (coreutils)[source]: Use it.

gnu/local.mk

@@ -928,6 +928,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/combinatorial-blas-awpm.patch		\
   %D%/packages/patches/combinatorial-blas-io-fix.patch		\
   %D%/packages/patches/connman-CVE-2021-33833.patch		\
+  %D%/packages/patches/coreutils-gnulib-tests.patch		\
   %D%/packages/patches/coreutils-ls.patch			\
   %D%/packages/patches/cpufrequtils-fix-aclocal.patch		\
   %D%/packages/patches/crawl-upgrade-saves.patch		\

gnu/packages/base.scm

@@ -328,7 +328,8 @@ (define-public coreutils
             (sha256
              (base32
               "1yjcrh5hw70c0yn8zw55pd6j51dj90anpq8mmg649ps9g3gdhn24"))
-            (patches (search-patches "coreutils-ls.patch"))))
+            (patches (search-patches "coreutils-ls.patch"
+                                     "coreutils-gnulib-tests.patch"))))
    (build-system gnu-build-system)
    (inputs `(("acl"  ,acl)                        ; TODO: add SELinux
              ("attr" ,attr)                       ;for xattrs in ls, mv, etc

gnu/packages/patches/coreutils-gnulib-tests.patch

@@ -0,0 +1,45 @@
+Fix Gnulib test failures showing up on ARMv7:
+
+  https://issues.guix.gnu.org/49459
+
+This is a backport of this Gnulib commit:
+
+  commit 175e0bc72808d564074c4adcc72aeadb74adfcc6
+  Author: Paul Eggert <eggert@cs.ucla.edu>
+  Date:   Thu Aug 27 17:52:58 2020 -0700
+
+      perror, strerror_r: remove unportable tests
+
+      Problem reported by Florian Weimer in:
+      https://lists.gnu.org/r/bug-gnulib/2020-08/msg00220.html
+      * tests/test-perror2.c (main):
+      * tests/test-strerror_r.c (main): Omit unportable tests.
+
+diff --git a/tests/test-perror2.c b/tests/test-perror2.c
+index 1d14eda7be..c6214dd25c 100644
+--- a/gnulib-tests/test-perror2.c
++++ b/gnulib-tests/test-perror2.c
+@@ -79,9 +79,6 @@ main (void)
+     errno = -5;
+     perror ("");
+     ASSERT (!ferror (stderr));
+-    ASSERT (msg1 == msg2 || msg1 == msg4 || STREQ (msg1, str1));
+-    ASSERT (msg2 == msg4 || STREQ (msg2, str2));
+-    ASSERT (msg3 == msg4 || STREQ (msg3, str3));
+     ASSERT (STREQ (msg4, str4));
+ 
+     free (str1);
+diff --git a/tests/test-strerror_r.c b/tests/test-strerror_r.c
+index b11d6fd9f6..c1dbcf837b 100644
+--- a/gnulib-tests/test-strerror_r.c
++++ b/gnulib-tests/test-strerror_r.c
+@@ -165,9 +165,6 @@ main (void)
+ 
+     strerror_r (EACCES, buf, sizeof buf);
+     strerror_r (-5, buf, sizeof buf);
+-    ASSERT (msg1 == msg2 || msg1 == msg4 || STREQ (msg1, str1));
+-    ASSERT (msg2 == msg4 || STREQ (msg2, str2));
+-    ASSERT (msg3 == msg4 || STREQ (msg3, str3));
+     ASSERT (STREQ (msg4, str4));
+ 
+     free (str1);