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);
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<div class='path'>path: <a href='/guix/log/?id=ea18b4c5298c8cdcea22472f8cf8ce8fb3180a78'>root</a>/<a href='/guix/log/.gitattributes?id=ea18b4c5298c8cdcea22472f8cf8ce8fb3180a78'>.gitattributes</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/.gitattributes?id=ea18b4c5298c8cdcea22472f8cf8ce8fb3180a78&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-10-14 00:24:34 +0200'>2021-10-14</span></td><td><a href='/guix/commit/.gitattributes?id=f8b10932c86cf4c1657a67e8c484d76f757b64bd'>Add git configuration templates to improve diff hunk header detection.</a><span class='msg-avail'>...<span class='msg-tooltip'>This is a follow-up to commit 9fc8ae4171e5da4939a64fc6d684c8b9d85bbe84, which
missed two hunks from &lt;https://issues.guix.gnu.org/50363&gt;.

Reported by hackeryarn on #guix.

* .gitattributes, etc/git/gitconfig: New files.

Signed-off-by: Marius Bakke &lt;marius@gnu.org&gt;
</span></span></td><td>Sarah Morgensen</td></tr>