GN: Remove duplicate entries from sources lists

printing/BUILD.gn

 # Copyright 2014 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/features.gni")
 import("//build/config/ui.gni")
 if (is_mac) {
   import("//build/config/mac/mac_sdk.gni")
 }
 if (is_android) {
@@ skipping 107 matching lines @@
   }
 
   if (is_chromeos) {
     sources += [
       "printing_context_no_system_dialog.cc",
       "printing_context_no_system_dialog.h",
     ]
   }
 
   if (use_cups) {
-    cups_version = exec_script("cups_config_helper.py", [ "--api-version" ],
-                               "trim string")
-
     configs += [ ":cups" ]
 
     if (is_linux) {
+      cups_version = exec_script("cups_config_helper.py", [ "--api-version" ],
+                                 "trim string")
+
       if (cups_version == "1.6" || cups_version == "1.7") {
         cflags += [
           # CUPS 1.6 deprecated the PPD APIs, but we will stay with this
           # API for now as supported Linux and Mac OS'es are still using
           # older versions of CUPS. More info: crbug.com/226176
           "-Wno-deprecated-declarations",
           # CUPS 1.7 deprecates httpConnectEncrypt(), see the mac section
           # below.
         ]
       }
@@ skipping 103 matching lines @@
   #  'type': 'none',
   #  'variables': {
   #    'java_in_dir': '../printing/android/java',
   #  },
   #  'dependencies': [
   #    '../base/base.gyp:base_java',
   #  ],
   #  'includes': [ '../build/java.gypi'  ],
   #}
 }