Fix oval rendering in vulkan

src/gpu/vk/GrVkCaps.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrVkCaps.h"
 
 #include "GrVkUtil.h"
@@ skipping 102 matching lines @@
     // fConfigOutputSwizzle will default to RGBA so we only need to set it for alpha only config.
     for (int i = 0; i < kGrPixelConfigCnt; ++i) {
         GrPixelConfig config = static_cast<GrPixelConfig>(i);
         if (GrPixelConfigIsAlphaOnly(config)) {
             glslCaps->fConfigTextureSwizzle[i] = GrSwizzle::RRRR();
             glslCaps->fConfigOutputSwizzle[i] = GrSwizzle::AAAA();
         } else {
             glslCaps->fConfigTextureSwizzle[i] = GrSwizzle::RGBA();
         }
     }
+
+    glslCaps->fShaderDerivativeSupport = true;

[egdaniel, 2016/02/25 21:07:23]

This should always be supported and I don't think we need to enable an extension
in the shader since SPIR-V has derivative support directly

 }
 
 static void format_supported_for_feature(const GrVkInterface* interface,
                                          VkPhysicalDevice physDev,
                                          VkFormat format,
                                          VkFormatFeatureFlagBits featureBit,
                                          bool* linearSupport,
                                          bool* optimalSupport) {
     VkFormatProperties props;
     memset(&props, 0, sizeof(VkFormatProperties));
@@ skipping 102 matching lines @@
                   // internal Format             stencil bits      total bits        packed?
         gS8    = { VK_FORMAT_S8_UINT,            8,                 8,               false },
         gD24S8 = { VK_FORMAT_D24_UNORM_S8_UINT,  8,                32,               true };
 
     // I'm simply assuming that these two will be supported since they are used in example code.
     // TODO: Actaully figure this out
     SET_CONFIG_CAN_STENCIL(gS8);
     SET_CONFIG_CAN_STENCIL(gD24S8);
 }