Fixes build with Python >= 3.6:

------
Making all in libgnomeui
make[2]: Entering directory '/tmp/guix-build-libgnomeui-2.24.5.drv-0/libgnomeui-2.24.5/libgnomeui'
  GEN    stamp-gnome-marshal.h
  GEN    stamp-gnometypebuiltins.h
INFO: Reading ./gnome-marshal.list...
  GEN    gnome-marshal.h
Traceback (most recent call last):
  File "/gnu/store/...-glib-2.54.2-bin/bin/glib-mkenums", line 688, in <module>
    process_file(fname)
  File "/gnu/store/...-glib-2.54.2-bin/bin/glib-mkenums", line 420, in process_file
    line = curfile.readline()
  File "/gnu/store/...-python-3.6.3/lib/python3.6/codecs.py", line 321, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xf1 in position 1009: invalid continuation byte
make[2]: *** [Makefile:1109: stamp-gnometypebuiltins.h] Error 1
make[2]: Leaving directory '/tmp/guix-build-libgnomeui-2.24.5.drv-0/libgnomeui-2.24.5/libgnomeui'
make[1]: *** [Makefile:369: all-recursive] Error 1
make[1]: Leaving directory '/tmp/guix-build-libgnomeui-2.24.5.drv-0/libgnomeui-2.24.5'
make: *** [Makefile:296: all] Error 2
------

Patch copied from upstream source repository:

https://git.gnome.org/browse/libgnomeui/commit/?id=30334c28794ef85d8973f4ed0779b5ceed6594f2

From 30334c28794ef85d8973f4ed0779b5ceed6594f2 Mon Sep 17 00:00:00 2001
From: Colin Walters <walters@verbum.org>
Date: Mon, 7 Aug 2017 13:15:26 -0400
Subject: [PATCH] gnome-scores.h: Convert to UTF-8

The new Python `glib-mkenums` barfs on ISO-8859-1 input.
---
 libgnomeui/gnome-scores.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libgnomeui/gnome-scores.h b/libgnomeui/gnome-scores.h
index 911b12d1..4e641d22 100644
--- a/libgnomeui/gnome-scores.h
+++ b/libgnomeui/gnome-scores.h
@@ -27,7 +27,7 @@
  * "High Scores" Widget 
  *
  * AUTHOR: 
- * Horacio J. Peña <horape@compendium.com.ar>
+ * Horacio J. Peña <horape@compendium.com.ar>
  *
  * This is free software (under the terms of the GNU LGPL)
  *
rm>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=7f7f2844ad8f7be42ce0f3287035b1a2a0ca9373'>root</a>/<a href='/guix/log/gnu?id=7f7f2844ad8f7be42ce0f3287035b1a2a0ca9373'>gnu</a>/<a href='/guix/log/gnu/packages?id=7f7f2844ad8f7be42ce0f3287035b1a2a0ca9373'>packages</a>/<a href='/guix/log/gnu/packages/opencog.scm?id=7f7f2844ad8f7be42ce0f3287035b1a2a0ca9373'>opencog.scm</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/gnu/packages/opencog.scm?id=7f7f2844ad8f7be42ce0f3287035b1a2a0ca9373&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-12-13 17:48:25 +0100'>2021-12-13</span></td><td><a href='/guix/commit/gnu/packages/opencog.scm?id=8394619baceb118df92e355377fd543bb1aa501a'>gnu: Simplify package inputs.</a><span class='msg-avail'>...<span class='msg-tooltip'>This commit was obtained by running:

  ./pre-inst-env guix style

without any additional argument.
</span></span></td><td>Ludovic Courtès</td></tr>
 pages.
* gnu/services/pm.scm (tlp-activation): Update configuration file name.
</span></span></td><td>Nicolas Goaziou</td></tr>
<tr><td><span title='2019-08-26 13:40:45 +0200'>2019-08-26</span></td><td><a href='/guix/commit/gnu/services/pm.scm?id=94b98ef7a089d7a5720a9af2369dc994eb7ffe9d'>services: tlp, thermald: Add descriptions.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/pm.scm (tlp-service-type)[description]: New field.
(thermald-service-type)[description]: New field.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-06-20 12:16:11 -0400'>2018-06-20</span></td><td><a href='/guix/commit/gnu/services/pm.scm?id=6a18183f4b82688bd4417d075d3f7ba20e008119'>services: Fix GPLv3 header in cuirass and pm modules.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/cuirass.scm, gnu/services/pm.scm: Adjust to canonical GPLv3
header used throughout Guix.

Signed-off-by: Leo Famulari &lt;leo@famulari.name&gt;
</span></span></td><td>Nils Gillmann</td></tr>
<tr><td><span title='2017-05-14 18:56:32 -0500'>2017-05-14</span></td><td><a href='/guix/commit/gnu/services/pm.scm?id=d7fa39ccec34bc223d52a04dfc3e1f756e2dfa24'>services: Add 'thermald-service-type'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/pm.scm (&lt;thermald-configuration&gt;): New record type.
(thermald-shepherd-service, thermald-service-type): New variables.
* doc/guix.texi (Thermal Management): New section documenting thermald.
</span></span></td><td>Christopher Allan Webber</td></tr>