Enable viewer in non-Vulkan builds

gyp/viewer.gyp

 # Copyright 2016 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 # GYP file to build performance testbench.
 #
 {
   'includes': [
     'apptype_console.gypi',
   ],
@@ skipping 60 matching lines @@
           # so we only include the minimum set of views files in sources
           'dependencies!': [
             'views.gyp:views',
           ],
           'link_settings': {
             'libraries': [
               '-landroid',
             ],
           },
         }],
-        [ 'skia_os == "linux"', {
+        [ 'skia_os == "linux" and skia_vulkan == 1', {
           'link_settings': {
             'libraries': [
               '-lX11-xcb',
             ],
           },
         }],
         ['skia_os != "android"', {
           'sources/': [
             ['exclude', '_android.(h|cpp)$'],
             ['exclude', 'src/views'],
           ],
         }],
         ['skia_os != "linux"', {
           'sources/': [
             ['exclude', '_unix.(h|cpp)$'],
             ['exclude', 'keysym2ucs.c'],
           ],
         }],
         ['skia_os != "win"', {
           'sources/': [ ['exclude', '_win.(h|cpp)$'],
           ],
         }],
+        ['skia_vulkan == 0', {
+          'sources/': [ ['exclude', 'Vulkan']
+          ],
+        }],
       ],
     },
   ],
 }