avformat/network: check for fcntl() failure in ff_socket()

Fixes: CID1087075
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/network.c

@@ -245,8 +245,10 @@ int ff_socket(int af, int type, int proto)
     {
         fd = socket(af, type, proto);
 #if HAVE_FCNTL
-        if (fd != -1)
-            fcntl(fd, F_SETFD, FD_CLOEXEC);
+        if (fd != -1) {
+            if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
+                av_log(NULL, AV_LOG_DEBUG, "Failed to set close on exec\n");
+        }
 #endif
     }
     return fd;