[libgrss] src: Fix check for return value from socket()

[Philip Withnall <pwithnall src gnome org>]

commit f47bef47dee12b6d0254d93bc427c6e7ec8b6025
Author: Philip Withnall <withnall endlessm com>
Date:   Wed Dec 21 16:53:11 2016 +0000

    src: Fix check for return value from socket()
    
    Failure is indicated by a negative number, not by 0. 0 is a valid FD,
    although it’s normally used by stdio.
    
    Coverity ID: 1388549
    
    https://bugzilla.gnome.org/show_bug.cgi?id=776115

 src/utils.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/utils.c b/src/utils.c
index 354c743..70f33c3 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -559,7 +559,7 @@ detect_internet_address ()
                return NULL;
 
        sockfd = socket (AF_INET, SOCK_DGRAM, 0);
-       if (!sockfd)
+       if (sockfd < 0)
                return NULL;
 
        if (connect (sockfd, (struct sockaddr*) &serv_add, sizeof (serv_add)) == -1) {