Revert of Enable viewer in non-Vulkan builds

tools/viewer/Viewer.cpp

Index: tools/viewer/Viewer.cpp
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index f44e1aac6b063e68fd72b26f55e145b5e59ab7c5..7052a3ac79244d7ee724ea9f23a900e675ef2b64 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -66,9 +66,7 @@
 
 const char *kBackendTypeStrings[sk_app::Window::kBackendTypeCount] = {
     " [OpenGL]",
-#ifdef SK_VULKAN
     " [Vulkan]",
-#endif
     " [Raster]"
 };
 
@@ -88,7 +86,7 @@
     : fCurrentMeasurement(0)
     , fDisplayStats(false)
     , fSplitScreen(false)
-    , fBackendType(sk_app::Window::kNativeGL_BackendType)
+    , fBackendType(sk_app::Window::kVulkan_BackendType)
     , fZoomCenterX(0.0f)
     , fZoomCenterY(0.0f)
     , fZoomLevel(0.0f)
@@ -104,10 +102,9 @@
 
     SkCommandLineFlags::Parse(argc, argv);
 
-#ifdef SK_VULKAN
     fBackendType = FLAGS_vulkan ? sk_app::Window::kVulkan_BackendType
                                 : sk_app::Window::kNativeGL_BackendType;
-#endif
+
     fWindow = Window::CreateNativeWindow(platformData);
     fWindow->attach(fBackendType, DisplayParams());