libSceNet: replace the always-fail stubs with a real offline network
stack. Sockets, epoll instances, memory pools and resolvers are tracked
in proper registries with create/destroy lifecycles; bind/listen/accept/
connect/send/recv/getsockopt/setsockopt/getsockname behave the way they
would on a console with no link up (bind and listen succeed locally,
connect/send fail with the errno a routeless host would give, blocking
calls such as accept/recv/epoll_wait return on close, abort or their
timeout). Infinite ("wait forever") timeouts are serviced in bounded
slices so a caller can never deadlock the process. Errno values match
the FreeBSD numbering the guest expects through sceNetErrnoLoc. Restored
sceNetGetsockopt and sceNetResolverStartAton (present upstream) using
the same registry-backed conventions as the rest of the rewrite.
libSceRudp: companion change giving the reliable-UDP library a genuine
context registry (init/create/bind/set-option/get-status) with
consistent error codes; connection attempts consistently fail since no
peer can ever be reached offline.