D3D11: Add a shader bytecode cache class

src/common/hash_combine.h

@@ -0,0 +1,10 @@
+// https://stackoverflow.com/questions/2590677/how-do-i-combine-hash-values-in-c0x
+#pragma once
+#include <functional>
+
+template<typename T, typename... Rest>
+void hash_combine(std::size_t& seed, const T& v, const Rest&... rest)
+{
+  seed ^= std::hash<T>{}(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+  (hash_combine(seed, rest), ...);
+}