Add gyp define to enable vulkan debug layers

On Debug vulkan bots, running with the debug layers on seems to be adding
more than an hour to the total running time. Since we suppress any output
on the bots anyways the debug layers are serving no purpose. Thus I am
adding a gyp define to disable the layers on the bot.

With this change, by default when running vulkan in Debug, the debug_layers
will be enabled. The bots should disable the layers. Android framework
should also have them disabled by default.

TBR=djsollen@google.com

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2185953003

Review-Url: https://codereview.chromium.org/2185953003
diff --git a/src/gpu/vk/GrVkGpu.cpp b/src/gpu/vk/GrVkGpu.cpp
index 7fddd4b..724a50d 100644
--- a/src/gpu/vk/GrVkGpu.cpp
+++ b/src/gpu/vk/GrVkGpu.cpp
@@ -44,7 +44,7 @@
 #define VK_CALL_RET(RET, X) GR_VK_CALL_RET(this->vkInterface(), RET, X)
 #define VK_CALL_ERRCHECK(X) GR_VK_CALL_ERRCHECK(this->vkInterface(), X)
 
-#ifdef ENABLE_VK_LAYERS
+#ifdef SK_ENABLE_VK_LAYERS
 VKAPI_ATTR VkBool32 VKAPI_CALL DebugReportCallback(
     VkDebugReportFlagsEXT       flags,
     VkDebugReportObjectTypeEXT  objectType,
@@ -93,7 +93,7 @@
     , fResourceProvider(this) {
     fBackendContext.reset(backendCtx);
 
-#ifdef ENABLE_VK_LAYERS
+#ifdef SK_ENABLE_VK_LAYERS
     fCallback = VK_NULL_HANDLE;
     if (backendCtx->fExtensions & kEXT_debug_report_GrVkExtensionFlag) {
         // Setup callback creation information
@@ -191,7 +191,7 @@
     shaderc_compiler_release(fCompiler);
 #endif
 
-#ifdef ENABLE_VK_LAYERS
+#ifdef SK_ENABLE_VK_LAYERS
     if (fCallback) {
         VK_CALL(DestroyDebugReportCallbackEXT(fBackendContext->fInstance, fCallback, nullptr));
         fCallback = VK_NULL_HANDLE;