network: deliver room datagrams through ProxySocket::Recv

When connected to an emulator room every guest socket is a ProxySocket.
Its Recv was a stub that always returned zero bytes, so games that read
UDP replies with recv() never received them. Mario Kart World LAN Play
reads its discovery replies this way, so guests never saw the host's
room in the LAN browser.

Delegate Recv to RecvFrom without an address, so queued room packets,
non-blocking, timeout, peek and truncation behaviour match recvfrom().

Assisted-by: Claude Opus 5.5 (investigation and implementation)

0 files changed, 0 insertions, 0 deletions