Fix GYP for nonxfa builds from last commit.

testing/libfuzzer/fuzzers.gyp

 # Copyright 2016 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.
 
 {
   'variables': {
     'pdf_enable_v8%': 1,
     'pdf_enable_xfa%': 0,  # Set to 1 in standalone builds by standalone.gypi.
   },
   'target_defaults': {
@@ skipping 17 matching lines @@
         ],
       }],
       ['pdf_enable_xfa==1', {
         'defines': [
           'PDF_ENABLE_XFA',
         ],
       }],
     ],
   },
   'conditions': [
-    ['pdf_enable_xfa==1 and OS!="win"', {
+    # FIXME(ochang): Make this work on Mac/Windows.
+    ['pdf_enable_xfa==1 and OS=="linux"', {
       'targets': [
         {
           'target_name': 'pdf_fm2js_fuzzer',
           'type': 'executable',
           'dependencies': [
             '../../pdfium.gyp:pdfium',
           ],
           'sources': [
             'pdf_fm2js_fuzzer.cc',
             'unittest_main.cc',
           ],
         },
         {
           'target_name': 'pdf_xml_fuzzer',
           'type': 'executable',
           'dependencies': [
             '../../pdfium.gyp:pdfium',
           ],
           'sources': [
             'pdf_xml_fuzzer.cc',
             'unittest_main.cc',
           ],
         },
       ],
     }],
-  ]
+  ],
+  # Empty target so that nonxfa builds work.
+  'targets': [
+    {
+      'target_name': 'empty_target',
+      'type': 'none',
+    }
+  ],
 }