Fix declaration of seed48().

According to various sources, `seed48()` returns a pointer.
(cherry picked from commit 3dd2fcdde63402ff4cc1a32a1ce42ef4345a419c)
Change type of sockaddr_un.sun_path on Solaris.

Use `byte` as any other OS. This fixes a compiler error in std.socket.
(cherry picked from commit 198bc18641f691b06c0facaeaa130d57c339637b)