treewide: use URN for fontconfig DTD

To match upstream change:

9c46ef4aac

nixos/modules/config/fonts/fontconfig.nix

@@ -35,7 +35,7 @@ let
     in
     pkgs.writeText "fc-00-nixos-cache.conf" ''
       <?xml version='1.0'?>
-      <!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
+      <!DOCTYPE fontconfig SYSTEM 'urn:fontconfig:fonts.dtd'>
       <fontconfig>
         <!-- Font directories -->
         ${concatStringsSep "\n" (map (font: "<dir>${font}</dir>") config.fonts.fonts)}
@@ -53,7 +53,7 @@ let
   # priority 10
   renderConf = pkgs.writeText "fc-10-nixos-rendering.conf" ''
     <?xml version='1.0'?>
-    <!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
+    <!DOCTYPE fontconfig SYSTEM 'urn:fontconfig:fonts.dtd'>
     <fontconfig>
 
       <!-- Default rendering settings -->
@@ -110,7 +110,7 @@ let
     in
     pkgs.writeText "fc-52-nixos-default-fonts.conf" ''
     <?xml version='1.0'?>
-    <!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
+    <!DOCTYPE fontconfig SYSTEM 'urn:fontconfig:fonts.dtd'>
     <fontconfig>
 
       <!-- Default fonts -->
@@ -129,7 +129,7 @@ let
   # priority 53
   rejectBitmaps = pkgs.writeText "fc-53-no-bitmaps.conf" ''
     <?xml version="1.0"?>
-    <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+    <!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
     <fontconfig>
 
     ${optionalString (!cfg.allowBitmaps) ''
@@ -157,7 +157,7 @@ let
   # priority 53
   rejectType1 = pkgs.writeText "fc-53-nixos-reject-type1.conf" ''
     <?xml version="1.0"?>
-    <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+    <!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
     <fontconfig>
 
     <!-- Reject Type 1 fonts -->

pkgs/applications/video/lightworks/default.nix

@@ -47,7 +47,7 @@ let
       # This adds it to lightworks' search path while keeping the default
       # using the FONTCONFIG_FILE env variable
       echo "<?xml version='1.0'?>
-      <!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
+      <!DOCTYPE fontconfig SYSTEM 'urn:fontconfig:fonts.dtd'>
       <fontconfig>
           <dir>/usr/share/fonts/truetype</dir>
           <include>/etc/fonts/fonts.conf</include>

pkgs/data/fonts/caladea/cambria-alias.conf

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
 <fontconfig>
   <!-- Configure Caladea as a metric-compatible alias for the
        Microsoft Cambria font family. -->

pkgs/data/fonts/carlito/calibri-alias.conf

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
 <fontconfig>
   <!-- Configure Carlito as a metric-compatible alias for the
        Microsoft Calibri font family. -->

pkgs/data/fonts/comic-relief/comic-sans-ms-alias.conf

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
 <fontconfig>
   <!-- Configure Comic Relief as a metric-compatible alias for the
        Microsoft Comic Sans font family. -->

pkgs/data/fonts/corefonts/no-op.conf

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
 <fontconfig>
   <!-- This configuation is intentionally left empty in order to
        override any other font package that may wish to set up an

pkgs/data/fonts/vista-fonts-chs/no-op.conf

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
 <fontconfig>
   <!-- This configuation is intentionally left empty in order to
        override any other font package that may wish to set up an

pkgs/data/fonts/vista-fonts/no-op.conf

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
 <fontconfig>
   <!-- This configuation is intentionally left empty in order to
        override any other font package that may wish to set up an

pkgs/development/libraries/fontconfig/make-fonts-cache.nix

@@ -16,7 +16,7 @@ runCommand "fc-cache"
 
     cat > fonts.conf << EOF
     <?xml version='1.0'?>
-    <!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
+    <!DOCTYPE fontconfig SYSTEM 'urn:fontconfig:fonts.dtd'>
     <fontconfig>
       <include>${fontconfig.out}/etc/fonts/fonts.conf</include>
       <cachedir>$out</cachedir>

pkgs/development/libraries/fontconfig/make-fonts-conf.xsl

@@ -12,7 +12,7 @@
                 extension-element-prefixes="str"
                 >
 
-  <xsl:output method='xml' encoding="UTF-8" doctype-system="fonts.dtd" />
+  <xsl:output method='xml' encoding="UTF-8" doctype-system="urn:fontconfig:fonts.dtd" />
 
   <xsl:param name="fontDirectories" />
   <xsl:param name="fontconfig" />