Skip Thai character test when libthai is unavailable.

Taken from upstream bug tracker:
https://gitlab.gnome.org/GNOME/pango/merge_requests/161
https://gitlab.gnome.org/GNOME/pango/commit/b73284747ac937e31dc9191f84ed6e24284c88ee

diff --git a/tests/test-break.c b/tests/test-break.c
index 8549b678bba69360d07dce3af21d915412f20d51..47fa3009165e19a331aa04a0df4351ae2323933b 100644
--- a/tests/test-break.c
+++ b/tests/test-break.c
@@ -305,6 +305,12 @@ main (int argc, char *argv[])
       if (!strstr (name, "break"))
         continue;
 
+#ifndef HAVE_LIBTHAI
+      /* four.break involves Thai, so only test it when we have libthai */
+      if (strstr (name, "four.break"))
+        continue;
+#endif
+
       path = g_strdup_printf ("/break/%s", name);
       g_test_add_data_func_full (path, g_test_build_filename (G_TEST_DIST, "breaks", name, NULL),
                                  test_break, g_free);
mized 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=f9f292f123274ff8bfb99b67a715e5c819c1b394'>refs</a><a class='active' href='/guix/log/scripts'>log</a><a href='/guix/tree/scripts?id=f9f292f123274ff8bfb99b67a715e5c819c1b394'>tree</a><a href='/guix/commit/scripts?id=f9f292f123274ff8bfb99b67a715e5c819c1b394'>commit</a><a href='/guix/diff/scripts?id=f9f292f123274ff8bfb99b67a715e5c819c1b394'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/scripts'>
<input type='hidden' name='id' value='f9f292f123274ff8bfb99b67a715e5c819c1b394'/><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=f9f292f123274ff8bfb99b67a715e5c819c1b394'>root</a>/<a href='/guix/log/scripts?id=f9f292f123274ff8bfb99b67a715e5c819c1b394'>scripts</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/scripts?id=f9f292f123274ff8bfb99b67a715e5c819c1b394&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
</a>/<a href='/guix/log/gnu/packages?id=fed6ac2ae182597a492b17a29ed8b26986498755'>packages</a>/<a href='/guix/log/gnu/packages/patches?id=fed6ac2ae182597a492b17a29ed8b26986498755'>patches</a>/<a href='/guix/log/gnu/packages/patches/ibus-anthy-fix-tests.patch?id=fed6ac2ae182597a492b17a29ed8b26986498755'>ibus-anthy-fix-tests.patch</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/patches/ibus-anthy-fix-tests.patch?id=fed6ac2ae182597a492b17a29ed8b26986498755&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-08-22 12:34:20 -0400'>2023-08-22</span></td><td><a href='/guix/commit/gnu/packages/patches/ibus-anthy-fix-tests.patch?id=13425768f7c393cda49302ba2e8705f14ae56f0d'>gnu: ibus-anthy: Update to 1.5.15.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/ibus.scm (ibus-anthy): Update to 1.5.15.
* gnu/packages/patches/ibus-anthy-fix-tests.patch: Update patch.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2023-06-14 11:05:30 -0400'>2023-06-14</span></td><td><a href='/guix/commit/gnu/packages/patches/ibus-anthy-fix-tests.patch?id=4e60cbe5bbcf425442952de0e8eb6410e9304d1d'>gnu: ibus-anthy: Prepare for tests.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/patches/ibus-anthy-fix-tests.patch: New patch.
* gnu/packages/ibus.scm (ibus-anthy): Register it.
* gnu/packages/ibus.scm (ibus-anthy) [source]: Apply patch.
[arguments]: Clarify #:tests? comment.  Add a fix-check,
do-not-override-GI_TYPELIB_PATH and prepare-for-tests phases.
[native-inputs]: Add procps, python-pycotap, util-linux and
xorg-server-for-tests.
</span></span></td><td>Maxim Cournoyer</td></tr>