vulkan_common: Move dynamic library load to a separate file

Allows us to initialize a Vulkan dynamic library from different backends
without duplicating code.

src/video_core/vulkan_common/vulkan_library.cpp

@@ -0,0 +1,36 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <cstdlib>
+#include <string>
+
+#include "common/dynamic_library.h"
+#include "common/file_util.h"
+#include "video_core/vulkan_common/vulkan_library.h"
+
+namespace Vulkan {
+
+Common::DynamicLibrary OpenLibrary() {
+    Common::DynamicLibrary library;
+#ifdef __APPLE__
+    // Check if a path to a specific Vulkan library has been specified.
+    char* const libvulkan_env = std::getenv("LIBVULKAN_PATH");
+    if (!libvulkan_env || !library.Open(libvulkan_env)) {
+        // Use the libvulkan.dylib from the application bundle.
+        const std::string filename =
+            Common::FS::GetBundleDirectory() + "/Contents/Frameworks/libvulkan.dylib";
+        library.Open(filename.c_str());
+    }
+#else
+    std::string filename = Common::DynamicLibrary::GetVersionedFilename("vulkan", 1);
+    if (!library.Open(filename.c_str())) {
+        // Android devices may not have libvulkan.so.1, only libvulkan.so.
+        filename = Common::DynamicLibrary::GetVersionedFilename("vulkan");
+        void(library.Open(filename.c_str()));
+    }
+#endif
+    return library;
+}
+
+} // namespace Vulkan

src/video_core/vulkan_common/vulkan_library.h

@@ -0,0 +1,13 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/dynamic_library.h"
+
+namespace Vulkan {
+
+Common::DynamicLibrary OpenLibrary();
+
+} // namespace Vulkan