Remove extra argument to a format string.

pcap_win32_err_to_str() already puts the error code into the
string.
diff --git a/sockutils.c b/sockutils.c
index 02d9a55..f694902 100644
--- a/sockutils.c
+++ b/sockutils.c
@@ -134,9 +134,9 @@
 
 	pcap_win32_err_to_str(errcode, message);
 	if ((caller) && (*caller))
-		pcap_snprintf(errbuf, errbuflen, "%s%s", caller, message, errcode);
+		pcap_snprintf(errbuf, errbuflen, "%s%s", caller, message);
 	else
-		pcap_snprintf(errbuf, errbuflen, "%s", message, errcode);
+		pcap_snprintf(errbuf, errbuflen, "%s", message);
 #else
 	char *message;