Add fonts from all XDG_DATA_DIRS, not just XDG_DATA_HOME.

See <http://bugs.gnu.org/41174>.
Author: Liliana Marie Prikler <liliana.prikler@gmail.com>
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.
 }
/installer/newt/hostname.scm?id=70102f9d83704e687f4f39fc9c5aec1da5ccddb5'>commit</a><a href='/guix/diff/gnu/installer/newt/hostname.scm?id=70102f9d83704e687f4f39fc9c5aec1da5ccddb5'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/installer/newt/hostname.scm'>
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<div class='path'>path: <a href='/guix/log/?id=70102f9d83704e687f4f39fc9c5aec1da5ccddb5'>root</a>/<a href='/guix/log/gnu?id=70102f9d83704e687f4f39fc9c5aec1da5ccddb5'>gnu</a>/<a href='/guix/log/gnu/installer?id=70102f9d83704e687f4f39fc9c5aec1da5ccddb5'>installer</a>/<a href='/guix/log/gnu/installer/newt?id=70102f9d83704e687f4f39fc9c5aec1da5ccddb5'>newt</a>/<a href='/guix/log/gnu/installer/newt/hostname.scm?id=70102f9d83704e687f4f39fc9c5aec1da5ccddb5'>hostname.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/installer/newt/hostname.scm?id=70102f9d83704e687f4f39fc9c5aec1da5ccddb5&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-01-17 14:04:25 +0100'>2019-01-17</span></td><td><a href='/guix/commit/gnu/installer/newt/hostname.scm?id=d700d131be31bd2838206bfc13ddd418affb185b'>installer: Make sure every sentence is dot terminated.</a><span class='msg-avail'>...<span class='msg-tooltip'>gnu/installer/newt/hostname.scm: Finish sentences by a dot.
gnu/installer/newt/network.scm: Ditto.
gnu/installer/newt/page.scm: Ditto.
gnu/installer/newt/partition.scm: Ditto.
gnu/installer/newt/user.scm: Ditto.
gnu/installer/newt/wifi.scm: Ditto.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2019-01-17 14:04:22 +0100'>2019-01-17</span></td><td><a href='/guix/commit/gnu/installer/newt/hostname.scm?id=5cdb6bd2db0b465fa616a9fd36760b14844d5c48'>installer: Remove "selection" from all titles.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/newt/hostname.scm (run-hostname-page): Remove selection from
page title,
(run-variant-page): ditto.
* gnu/installer/newt/keymap.scm (run-layout-page): Ditto.
* gnu/installer/newt/locale.scm (run-layout-page): Ditto,
(run-territory-page): ditto,
(run-codeset-page): ditto,
(run-modifier-page): ditto
* gnu/installer/newt/network.scm (run-territory-page): Ditto.
* gnu/installer/newt/timezone.scm (run-timezone-page): Ditto.
* gnu/installer/newt/wifi.scm (run-wifi-page): Ditto.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2019-01-17 14:04:20 +0100'>2019-01-17</span></td><td><a href='/guix/commit/gnu/installer/newt/hostname.scm?id=d0f3a672dcbdfefd3556b6a21985ff0e35eed3be'>gnu: Add graphical installer support.</a><span class='msg-avail'>...<span class='msg-tooltip'>* configure.ac: Require that guile-newt is available.
* gnu/installer.scm: New file.
* gnu/installer/aux-files/logo.txt: New file.
* gnu/installer/build-installer.scm: New file.
* gnu/installer/connman.scm: New file.
* gnu/installer/keymap.scm: New file.
* gnu/installer/locale.scm: New file.
* gnu/installer/newt.scm: New file.
* gnu/installer/newt/ethernet.scm: New file.
* gnu/installer/newt/hostname.scm: New file.
* gnu/installer/newt/keymap.scm: New file.
* gnu/installer/newt/locale.scm: New file.
* gnu/installer/newt/menu.scm: New file.
* gnu/installer/newt/network.scm: New file.
* gnu/installer/newt/page.scm: New file.
* gnu/installer/newt/timezone.scm: New file.
* gnu/installer/newt/user.scm: New file.
* gnu/installer/newt/utils.scm: New file.
* gnu/installer/newt/welcome.scm: New file.
* gnu/installer/newt/wifi.scm: New file.
* gnu/installer/steps.scm: New file.
* gnu/installer/timezone.scm: New file.
* gnu/installer/utils.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add previous files.
* gnu/system.scm: Export %root-account.
* gnu/system/install.scm (%installation-services): Use kmscon instead of linux
VT for all tty.
(installation-os)[users]: Add the graphical installer as shell of the root
account.
[packages]: Add font related packages.
* po/guix/POTFILES.in: Add installer files.
</span></span></td><td>Mathieu Othacehe</td></tr>