concepts: fix review notes

Utilities/File.h

@@ -1,5 +1,6 @@
 #pragma once // No BOM and only basic ASCII in this header, or a neko will die
 
+#include "util/serialization.hpp"
 #include "util/types.hpp"
 #include "util/shared_ptr.hpp"
 #include "bit_set.h"
@@ -78,6 +79,8 @@ namespace fs
 		constexpr bool operator==(const stat_t&) const = default;
 	};
 
+	static_assert(utils::Bitcopy<stat_t>);
+
 	// Helper, layout is equal to iovec struct
 	struct iovec_clone
 	{
@@ -126,6 +129,8 @@ namespace fs
 		using enable_bitcopy = std::false_type;
 	};
 
+	static_assert(!utils::Bitcopy<dir_entry>);
+
 	// Directory handle base
 	struct dir_base
 	{

Utilities/StrFmt.h

@@ -130,7 +130,7 @@ struct fmt_unveil<se_t<T, Se, Align>>
 };
 
 // String type format provider, also type classifier (format() called if an argument is formatted as "%s")
-template <typename T, typename = void>
+template <typename T>
 struct fmt_class_string
 {
 	// Formatting function (must be explicitly specialized)
@@ -215,7 +215,7 @@ struct fmt_class_string<T*> : fmt_class_string<const void*>
 };
 
 template <>
-struct fmt_class_string<const char*, void>
+struct fmt_class_string<const char*>
 {
 	static void format(std::string& out, u64 arg);
 };
@@ -237,7 +237,7 @@ struct fmt_class_string<char8_t*> : fmt_class_string<const char8_t*>
 };
 
 template <>
-struct fmt_class_string<const wchar_t*, void>
+struct fmt_class_string<const wchar_t*>
 {
 	static void format(std::string& out, u64 arg);
 };
@@ -257,7 +257,7 @@ namespace fmt
 }
 
 template <fmt::StringConvertible T>
-struct fmt_class_string<T, void>
+struct fmt_class_string<T>
 {
 	static FORCE_INLINE SAFE_BUFFERS(const T&) get_object(u64 arg)
 	{
@@ -278,7 +278,7 @@ namespace fmt
 }
 
 template <fmt::ByteArray T>
-struct fmt_class_string<T, void>
+struct fmt_class_string<T>
 {
 	static FORCE_INLINE SAFE_BUFFERS(const T&) get_object(u64 arg)
 	{