tipc: fix inconsistent signal handling regression

Commit 9bbb4ecc ("tipc: standardize recvmsg routine") changed
the sleep/wakeup behaviour for sockets entering recv() or accept().
In this process the order of reporting -EAGAIN/-EINTR was reversed.
This caused problems with wrong errno being reported back if the
timeout expires. The same problem happens if the socket is
nonblocking and recv()/accept() is called when the process have
pending signals. If there is no pending data read or connections to
accept, -EINTR will be returned instead of -EAGAIN.

Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Reported-by László Benedek <laszlo.benedek@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>