Clear num_opts early

If we error out, it could be garbage.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/init.c b/init.c
index 9169977..652b2e2 100644
--- a/init.c
+++ b/init.c
@@ -637,6 +637,7 @@
 
 	alloc_opts = 8;
 	opts = malloc(sizeof(char *) * alloc_opts);
+	num_opts = 0;
 
 	stonewall = stonewall_flag;
 	do {