clean up byteorder.hh

byteorder.hh's "net::packed<T>" subclassed the basic unaligned<T> and
added a "adjust_endianess" method. This was completely unnecessary:
While ntoh's generic implementation indeed uses that method, we also
have a specialized overload for ntoh(packed<T>), so the generic
implementation would never be used for packed<T> anyway!

So for net::packed<T> we don't need anything more than unaligned<T>,
and can just make it an alias.

As a bonus, the "hton" function will now work also on unaligned<T>
(such as the result of the convenient unaligned_cast<>), not just on
net::packed<T>.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>

net/byteorder.hh

@@ -58,13 +58,9 @@ inline int32_t hton(int32_t x) { return htonl(x); }
 inline int64_t ntoh(int64_t x) { return ntohq(x); }
 inline int64_t hton(int64_t x) { return htonq(x); }
 
-// Define net::packed<> using unaligned<> from unaligned.hh.
-template <typename T>
-struct packed : public unaligned<T> {
-    using unaligned<T>::unaligned; // inherit constructors
-    template <typename Adjuster>
-    void adjust_endianness(Adjuster a) { a(this->raw); }
-} __attribute__((packed));
+// Deprecated alias net::packed<> for unaligned<> from unaligned.hh.
+// TODO: get rid of this alias.
+template <typename T> using packed = unaligned<T>;
 
 template <typename T>
 inline T ntoh(const packed<T>& x) {