stream-tcp: Call setsockopt TCP_NODELAY after TCP is connected.

On Windows platform, TCP_NODELAY can only be set when TCP is established.
(This is an observed behavior and not written in any MSDN documentation.)
The current code does not create any problems while running unit tests
(because connections get established immediately) but is reportedly
observed while connecting to a different machine.

commit 8b76839(Move setsockopt TCP_NODELAY to when TCP is connected.)
made changes to call setsockopt with TCP_NODELAY after TCP is connected
only in lib/stream-ssl.c. We need the same change for stream-tcp too and
this commit does that.

Currently, a failure of setting TCP_NODELAY results in reporting
the error and then closing the socket. This commit changes that
behavior such that an error is reported if setting TCP_NODELAY
fails, but the connection itself is not torn down.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

lib/socket-util.c

@@ -21,6 +21,7 @@
 #include <fcntl.h>
 #include <net/if.h>
 #include <netdb.h>
+#include <netinet/tcp.h>
 #include <poll.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -87,6 +88,19 @@ xset_nonblocking(int fd)
     }
 }
 
+void
+setsockopt_tcp_nodelay(int fd)
+{
+    int on = 1;
+    int retval;
+
+    retval = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof on);
+    if (retval) {
+        retval = sock_errno();
+        VLOG_ERR("setsockopt(TCP_NODELAY): %s", sock_strerror(retval));
+    }
+}
+
 int
 set_dscp(int fd, uint8_t dscp)
 {