Support limited mixed command line options and job file

With this, you can now do:

$ fio --timeout=10s --time_based=1 jobfile.fio

and have the command line options work as if they were part
of the global section of jobfile.fio

Note that more advanced uses, like:

$ fio --option_foo=1 jobfile.fio --option_bar=1 jobfile2.fio

will not work, we still clear to default options for
subsequent jobs.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/init.c b/init.c
index 11876b9..e9e49eb 100644
--- a/init.c
+++ b/init.c
@@ -2033,7 +2033,7 @@
 
 	if (job_files > 0) {
 		for (i = 0; i < job_files; i++) {
-			if (fill_def_thread())
+			if (i && fill_def_thread())
 				return 1;
 			if (nr_clients) {
 				if (fio_clients_send_ini(ini_file[i]))