Move default value of pdf_enable_xfa to standalone.gypi

build/standalone.gypi

 # Copyright 2014 PDFium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Definitions to be used when building stand-alone PDFium binaries.
 
 {
   'variables': {
     'component%': 'static_library',
     'clang%': 0,
     'asan%': 0,
     'sanitizer_coverage%': 0,
     'use_goma%': 0,
     'gomadir%': '',
     'msvs_multi_core_compile%': '1',
+    'pdf_enable_xfa%': 1,
     'variables': {
       'variables': {
         'variables': {
           'conditions': [
             ['OS=="linux" or OS=="mac"', {
               # This handles the Unix platforms we generally deal with.
               # Anything else gets passed through, which probably won't work
               # very well; such hosts should pass an explicit target_arch
               # to gyp.
               'host_arch%':
@@ skipping 309 matching lines @@
       ],
     }],  # OS=="linux" or OS=="mac"
     ["use_goma==1", {
       'make_global_settings': [
         ['CC_wrapper', '<(gomadir)/gomacc'],
         ['CXX_wrapper', '<(gomadir)/gomacc'],
       ],
     }],  # use_goma==1
   ],
 }