Epsocket has incorrect recv(2) behavior after SHUT_RD.
Epsocket has incorrect recv(2) behavior after SHUT_RD.

After shutdown(SHUT_RD) calls to recv /w MSG_DONTWAIT or with
O_NONBLOCK should result in a EAGAIN and not 0. Blocking sockets
should return 0 as they would have otherwise blocked indefinitely.

PiperOrigin-RevId: 201271123
Change-Id: If589b69c17fa5b9ff05bcf9e44024da9588c8876

google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor