[GN] Guard the "pangocairo" config with (use_pango || use_cairo).

build/config/linux/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/linux/pkg_config.gni")
 import("//build/config/features.gni")
 import("//build/config/sysroot.gni")
 import("//build/config/ui.gni")
 
 # This is included by reference in the //build/config/compiler config that
@@ skipping 28 matching lines @@
 
 pkg_config("glib") {
   packages = [
     "glib-2.0",
     "gmodule-2.0",
     "gobject-2.0",
     "gthread-2.0",
   ]
 }
 
-pkg_config("pangocairo") {
-  packages = [ "pangocairo" ]
+if (use_pango || use_cairo) {
+  pkg_config("pangocairo") {
+    packages = [ "pangocairo" ]
+  }
 }
 
-pkg_config("pangoft2") {
-  packages = [ "pangoft2" ]
+if (use_pango) {
+  pkg_config("pangoft2") {
+    packages = [ "pangoft2" ]
+  }
 }
 
 # Note: if your target also depends on //dbus, you don't need to add this
 # config (it will get added automatically if you depend on //dbus).
 pkg_config("dbus") {
   packages = [ "dbus-1" ]
 }
 
 pkg_config("libffi") {
   packages = [ "libffi" ]
@@ skipping 80 matching lines @@
         "-Wno-unused-function",
       ]
     }
 
     pkg_config("gconf") {
       packages = [ "gconf-2.0" ]
       defines = [ "USE_GCONF" ]
     }
   }
 }