Enable viewer in non-Vulkan builds

tools/viewer/sk_app/unix/Window_unix.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 //#include <tchar.h>
 
 #include "SkUtils.h"
 #include "Timer.h"
 #include "../GLWindowContext.h"
+#ifdef SK_VULKAN
 #include "../VulkanWindowContext.h"
+#endif
 #include "Window_unix.h"
 
 extern "C" {
     #include "keysym2ucs.h"
 }
 #include <X11/Xutil.h>
 #include <X11/XKBlib.h>
 
 namespace sk_app {
 
@@ skipping 245 matching lines @@
 }
 
 bool Window_unix::attach(BackendType attachType, const DisplayParams& params) {
     this->initWindow(fDisplay, &params);
 
     ContextPlatformData_unix platformData;
     platformData.fDisplay = fDisplay;
     platformData.fWindow = fWindow;
     platformData.fVisualInfo = fVisualInfo;
     switch (attachType) {
+#ifdef SK_VULKAN
         case kVulkan_BackendType:
             fWindowContext = VulkanWindowContext::Create((void*)&platformData, params);
             break;
-
+#endif
         case kNativeGL_BackendType:
         default:
             fWindowContext = GLWindowContext::Create((void*)&platformData, params);
             break;
     }
 
     return (SkToBool(fWindowContext));
 }
 
 void Window_unix::onInval() {
     XEvent event;
     event.type = Expose;
     event.xexpose.send_event = True;
     event.xexpose.display = fDisplay;
     event.xexpose.window = fWindow;
     event.xexpose.x = 0;
     event.xexpose.y = 0;
     event.xexpose.width = fWidth;
     event.xexpose.height = fHeight;
     event.xexpose.count = 0;
     
     XSendEvent(fDisplay, fWindow, False, 0, &event);
 }
 
 }   // namespace sk_app