Add test configs for instanced rendering

src/gpu/vk/GrVkGpu.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrVkGpu_DEFINED
 #define GrVkGpu_DEFINED
 
@@ skipping 164 matching lines @@
 
     GrTexture* onWrapBackendTexture(const GrBackendTextureDesc&, GrWrapOwnership) override;
 
     GrRenderTarget* onWrapBackendRenderTarget(const GrBackendRenderTargetDesc&,
                                               GrWrapOwnership) override;
     GrRenderTarget* onWrapBackendTextureAsRenderTarget(const GrBackendTextureDesc&) override { return NULL; }
 
     GrBuffer* onCreateBuffer(size_t size, GrBufferType type, GrAccessPattern,
                              const void* data) override;
 
+    gr_instanced::InstancedRendering* onCreateInstancedRendering() override { return nullptr; }
+
     bool onReadPixels(GrSurface* surface,
                       int left, int top, int width, int height,
                       GrPixelConfig,
                       void* buffer,
                       size_t rowBytes) override;
 
     bool onWritePixels(GrSurface* surface,
                        int left, int top, int width, int height,
                        GrPixelConfig config, const SkTArray<GrMipLevel>&) override;
 
@@ skipping 65 matching lines @@
 #else
     // Shaderc compiler used for compiling glsl in spirv. We only want to create the compiler once
     // since there is significant overhead to the first compile of any compiler.
     shaderc_compiler_t fCompiler;
 #endif
 
     typedef GrGpu INHERITED;
 };
 
 #endif