yuzu: Implement Vulkan frontend

Adds a Qt and SDL2 frontend for Vulkan. It also finishes the missing
bits on Vulkan initialization.

src/yuzu_cmd/emu_window/emu_window_sdl2_vk.h

@@ -0,0 +1,39 @@
+// Copyright 2018 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <vulkan/vulkan.h>
+#include "core/frontend/emu_window.h"
+#include "yuzu_cmd/emu_window/emu_window_sdl2.h"
+
+class EmuWindow_SDL2_VK final : public EmuWindow_SDL2 {
+public:
+    explicit EmuWindow_SDL2_VK(bool fullscreen);
+    ~EmuWindow_SDL2_VK();
+
+    /// Swap buffers to display the next frame
+    void SwapBuffers() override;
+
+    /// Makes the graphics context current for the caller thread
+    void MakeCurrent() override;
+
+    /// Releases the GL context from the caller thread
+    void DoneCurrent() override;
+
+    /// Retrieves Vulkan specific handlers from the window
+    void RetrieveVulkanHandlers(void* get_instance_proc_addr, void* instance,
+                                void* surface) const override;
+
+    std::unique_ptr<Core::Frontend::GraphicsContext> CreateSharedContext() const override;
+
+private:
+    bool UseStandardLayers(PFN_vkGetInstanceProcAddr vkGetInstanceProcAddr) const;
+
+    VkInstance instance{};
+    VkSurfaceKHR surface{};
+
+    PFN_vkGetInstanceProcAddr vkGetInstanceProcAddr{};
+    PFN_vkDestroyInstance vkDestroyInstance{};
+};