Fix parse strlen() bug

Commit 38789b58775ee5e00f4669f01b3c9da31a7345e3 checks the wrong
string, it's unitialized garbage.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/parse.c b/parse.c
index d8527b5..9e3c5b1 100644
--- a/parse.c
+++ b/parse.c
@@ -658,7 +658,7 @@
 	ssize_t nchr = OPT_LEN_MAX;
 	size_t envlen;
 
-	if (strlen(in) + 1 > OPT_LEN_MAX) {
+	if (strlen(opt) + 1 > OPT_LEN_MAX) {
 		fprintf(stderr, "OPT_LEN_MAX (%d) is too small\n", OPT_LEN_MAX);
 		return NULL;
 	}