BUG/MINOR: cfgparse: fix typo in 'option httplog' error message

The error message was displaying the wrong argument when 'option
httplog' took a wrong argument.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index a030723..154802e 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -4132,7 +4132,7 @@
 					curproxy->options2 |= PR_O2_CLFLOG;
 					logformat = clf_http_log_format;
 				} else {
-					Alert("parsing [%s:%d] : keyword '%s' only supports option 'clf'.\n", file, linenum, args[2]);
+					Alert("parsing [%s:%d] : keyword '%s' only supports option 'clf'.\n", file, linenum, args[1]);
 					err_code |= ERR_ALERT | ERR_FATAL;
 					goto out;
 				}