Introduce struct hash<vk::Flags<BitType>>

Allows the use of any vk::*Flags type as the key in a std::unordered_map

vulkan/vulkan.hpp

@@ -13263,6 +13263,16 @@ namespace std
   //=== HASH structures ===
   //=======================
 
+  template <typename BitType>
+  struct hash<VULKAN_HPP_NAMESPACE::Flags<BitType>>
+  {
+    std::size_t operator()( VULKAN_HPP_NAMESPACE::Flags<BitType> const & flags ) const VULKAN_HPP_NOEXCEPT
+    {
+      return std::hash<typename std::underlying_type<BitType>::type>{}(
+        static_cast<typename std::underlying_type<BitType>::type>( flags ) );
+    }
+  };
+
   //=== VK_VERSION_1_0 ===
 
   template <>