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->__(
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<tr><td><span title='2020-08-18 22:56:26 +0200'>2020-08-18</span></td><td><a href='/guix/commit/gnu/packages/speech.scm?id=8dde7a8694d8ec032cb3f3c0302f3e124677cef6'>gnu: Add flite.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/speech.scm (flite): New variable.

Signed-off-by: Danny Milosavljevic &lt;dannym@scratchpost.org&gt;
</span></span></td><td>Raghav Gururajan</td></tr>
<tr><td><span title='2020-07-29 12:45:36 +0300'>2020-07-29</span></td><td><a href='/guix/commit/gnu/packages/speech.scm?id=eb9f726d22751dd77984b106f2dbf1c0d336954b'>gnu: sphinxbase: Fix building.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/speech.scm (sphinxbase)[source]: Add patch.
* gnu/packages/patches/sphinxbase-fix-doxygen.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2020-03-31 14:30:39 +0200'>2020-03-31</span></td><td><a href='/guix/commit/gnu/packages/speech.scm?id=5acea98e4b38ef4cdc1a8cebf6f784d9fcac9288'>gnu: sonic: Fix installation directories.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/speech.scm (sonic)[arguments]: Replace erroneous use of
DESTDIR with PREFIX.  Add the required ‘rpath’ LDFLAGS together with a
‘respect-LDFLAGS’ phase.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-03-29 22:32:54 +0200'>2020-03-29</span></td><td><a href='/guix/commit/gnu/packages/speech.scm?id=9e9dd4098f7a2de658625a0e803d4955ce6ba8fd'>gnu: Add pocketsphinx.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/speech.scm (pocketsphinx): New variable.
</span></span></td><td>Nicolas Goaziou</td></tr>
<tr><td><span title='2020-03-29 22:32:53 +0200'>2020-03-29</span></td><td><a href='/guix/commit/gnu/packages/speech.scm?id=337fc72228df2b01f024c1276703ea4369cee37d'>gnu: Add sphinxbase.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/speech.scm (sphinxbase): New variable.
</span></span></td><td>Nicolas Goaziou</td></tr>
<tr><td><span title='2020-02-24 17:10:21 +0100'>2020-02-24</span></td><td><a href='/guix/commit/gnu/packages/speech.scm?id=f175fa49875c4b756277370a225f919f24503ac6'>gnu: espeak-ng: Update to 1.50.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/speech.scm (espeak-ng): Update to 1.50.
[source]: Change to GIT-FETCH.
[native-inputs]: Add AUTOCONF, AUTOMAKE, LIBTOOL, and WHICH.
</span></span></td><td>Marius Bakke</td></tr>