Fix a deprecation warning with newer Perl that breaks some tests.

--- a/tp/Texinfo/Parser.pm
+++ b/tp/Texinfo/Parser.pm
@@ -5438,12 +5438,12 @@
     }
   } elsif ($command eq 'clickstyle') {
     # REMACRO
-    if ($line =~ /^\s+@([[:alnum:]][[:alnum:]\-]*)({})?\s*/) {
+    if ($line =~ /^\s+@([[:alnum:]][[:alnum:]\-]*)(\{})?\s*/) {
       $args = ['@'.$1];
       $self->{'clickstyle'} = $1
         unless(_ignore_global_commands($self));
       $remaining = $line;
-      $remaining =~ s/^\s+@([[:alnum:]][[:alnum:]\-]*)({})?\s*(\@(c|comment)((\@|\s+).*)?)?//;
+      $remaining =~ s/^\s+@([[:alnum:]][[:alnum:]\-]*)(\{})?\s*(\@(c|comment)((\@|\s+).*)?)?//;
       $has_comment = 1 if (defined($4));
     } else {
       $self->line_error (sprintf($self->__(
lected'>koszko</option>
<option value='koszko-scripts'>koszko-scripts</option>
</select> <input type='submit' value='switch'/></form></td></tr>
<tr><td class='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
<table class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=f38d8e050e8ff2bf00dd6f8b6f3aaf638663b9bb'>refs</a><a class='active' href='/guix/log/tests/guix-download.sh'>log</a><a href='/guix/tree/tests/guix-download.sh?id=f38d8e050e8ff2bf00dd6f8b6f3aaf638663b9bb'>tree</a><a href='/guix/commit/tests/guix-download.sh?id=f38d8e050e8ff2bf00dd6f8b6f3aaf638663b9bb'>commit</a><a href='/guix/diff/tests/guix-download.sh?id=f38d8e050e8ff2bf00dd6f8b6f3aaf638663b9bb'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/guix-download.sh'>
<input type='hidden' name='id' value='f38d8e050e8ff2bf00dd6f8b6f3aaf638663b9bb'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=f38d8e050e8ff2bf00dd6f8b6f3aaf638663b9bb'>root</a>/<a href='/guix/log/tests?id=f38d8e050e8ff2bf00dd6f8b6f3aaf638663b9bb'>tests</a>/<a href='/guix/log/tests/guix-download.sh?id=f38d8e050e8ff2bf00dd6f8b6f3aaf638663b9bb'>guix-download.sh</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/tests/guix-download.sh?id=f38d8e050e8ff2bf00dd6f8b6f3aaf638663b9bb&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-09-28 21:06:36 -0500'>2020-09-28</span></td><td><a href='/guix/commit/tests/guix-download.sh?id=d8934360d2453a403b5433e71d09188e4ed23b57'>tests: Simplify shell exit status negation;</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/guix-archive.sh, tests/guix-build-branch.sh, tests/guix-build.sh,
tests/guix-daemon.sh, tests/guix-download.sh, tests/guix-environment.sh,
tests/guix-gc.sh, tests/guix-git-authenticate.sh, tests/guix-graph.sh,
tests/guix-hash.sh, tests/guix-lint.sh, tests/guix-pack-relocatable.sh,
tests/guix-pack.sh, tests/guix-package-aliases.sh, tests/guix-package-net.sh,
tests/guix-package.sh: Use the shell '!' keyword to negate command exit status
in place of 'if ...; then false; else true; fi'
</span></span></td><td>Eric Bavier</td></tr>