Fix descriptor leak. Close #3848.

src/anet.c

@@ -380,8 +380,10 @@ int anetUnixGenericConnect(char *err, char *path, int flags)
     sa.sun_family = AF_LOCAL;
     strncpy(sa.sun_path,path,sizeof(sa.sun_path)-1);
     if (flags & ANET_CONNECT_NONBLOCK) {
-        if (anetNonBlock(err,s) != ANET_OK)
+        if (anetNonBlock(err,s) != ANET_OK) {
+            close(s);
             return ANET_ERR;
+        }
     }
     if (connect(s,(struct sockaddr*)&sa,sizeof(sa)) == -1) {
         if (errno == EINPROGRESS &&