merging some things from Ryan C. Gordon (icculus):

enet_socket_connect() shouldn't fail with non-blocking sockets.
Removed unused variable.
Sanity check for possible NULL dereference reported by clang's static…analysis.
Added an interface to shutdown().
Fixed typo in the comments.

unix.c

@@ -254,6 +254,7 @@ int
 enet_socket_connect (ENetSocket socket, const ENetAddress * address)
 {
     struct sockaddr_in sin;
+    int result;
 
     memset (& sin, 0, sizeof (struct sockaddr_in));
 
@@ -261,7 +262,11 @@ enet_socket_connect (ENetSocket socket, const ENetAddress * address)
     sin.sin_port = ENET_HOST_TO_NET_16 (address -> port);
     sin.sin_addr.s_addr = address -> host;
 
-    return connect (socket, (struct sockaddr *) & sin, sizeof (struct sockaddr_in));
+    result = connect (socket, (struct sockaddr *) & sin, sizeof (struct sockaddr_in));
+    if (result == -1 && errno == EINPROGRESS)
+      return 0;
+
+    return result;
 }
 
 ENetSocket
@@ -287,6 +292,12 @@ enet_socket_accept (ENetSocket socket, ENetAddress * address)
     return result;
 } 
     
+int
+enet_socket_shutdown (ENetSocket socket, ENetSocketShutdown how)
+{
+    return shutdown (socket, (int) how);
+}
+
 void
 enet_socket_destroy (ENetSocket socket)
 {