Add fonts from all XDG_DATA_DIRS, not just XDG_DATA_HOME.

See <http://bugs.gnu.org/41174>.
Author: Leo Prikler <leo.prikler@student.tugraz.at>
Index: webkitgtk-2.28.2/Source/WebKit/UIProcess/Launcher/glib/BubblewrapLauncher.cpp
===================================================================
--- a/Source/WebKit/UIProcess/Launcher/glib/BubblewrapLauncher.cpp
+++ b/Source/WebKit/UIProcess/Launcher/glib/BubblewrapLauncher.cpp
@@ -387,6 +387,7 @@ static void bindFonts(Vector<CString>& args)
     const char* homeDir = g_get_home_dir();
     const char* dataDir = g_get_user_data_dir();
     const char* cacheDir = g_get_user_cache_dir();
+    const char* const * dataDirs = g_get_system_data_dirs();

     // Configs can include custom dirs but then we have to parse them...
     GUniquePtr<char> fontConfig(g_build_filename(configDir, "fontconfig", nullptr));
@@ -403,6 +404,10 @@ static void bindFonts(Vector<CString>& args)
     bindIfExists(args, fontHomeConfigDir.get());
     bindIfExists(args, fontData.get());
     bindIfExists(args, fontHomeData.get());
+    for (auto dataDir = dataDirs; dataDir != nullptr && *dataDir != nullptr; dataDir++) {
+        GUniquePtr<char> fontDataDir(g_build_filename(*dataDir, "fonts", nullptr));
+        bindIfExists(args, fontDataDir.get());
+    }
     bindIfExists(args, "/var/cache/fontconfig"); // Used by Debian.
 }
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<tr><td><span title='2023-01-08 23:20:59 +0100'>2023-01-08</span></td><td><a href='/guix/commit/gnu/packages/axoloti.scm?id=a4d9ce54880dc0d299e4489a168398440c9e7c33'>gnu: Move Java XML packages to new module.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/xml.scm (java-simple-xml, java-jaxp,
java-apache-xml-commons-resolver, java-jaxen, java-xom, java-xsdlib,
java-xpp3, java-xmlpull2, java-xmlpull-api-v1, java-dom4j, java-kxml2,
java-stax, java-jettison, java-jdom2, java-xstream, java-mxparser): Move these
variables from here...
* gnu/packages/java-xml.scm: ...to this new file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Register new file.
* gnu/packages/axoloti.scm,
gnu/packages/batik.scm,
gnu/packages/bioinformatics.scm,
gnu/packages/groovy.scm,
gnu/packages/java.scm,
gnu/packages/maven.scm: Adjust module imports.
</span></span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2022-11-11 18:09:58 +0100'>2022-11-11</span></td><td><a href='/guix/commit/gnu/packages/axoloti.scm?id=09562e0bead3313e3e46a5fc0763f027a6bced3a'>gnu: axoloti: Remove unused module import.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/axoloti.scm (axoloti-runtime, axoloti-patcher,
axoloti-patcher-next)[arguments]: Don't import (guix build syscalls).
</span></span></td><td>Marius Bakke</td></tr>