Add missing assert.

ChangeLog

+2017-08-26  Niels Möller  <nisse@lysator.liu.se>
+
+	* ecc-mod-inv.c (ecc_mod_inv): Add missing assert. Fixes a
+	"dead increment" warning from the clang static analyzer.
+
 2017-07-18  Niels Möller  <nisse@lysator.liu.se>
 
 	* ecc-add-eh.c (ecc_add_eh): Fix in-place operation by reordering

ecc-mod-inv.c

@@ -145,6 +145,7 @@ ecc_mod_inv (const struct ecc_modulo *m,
       cnd_swap (swap, up, vp, n);
       cy = cnd_sub_n (odd, up, vp, n);
       cy -= cnd_add_n (cy, up, m->m, n);
+      assert (cy == 0);
 
       cy = mpn_rshift (ap, ap, n, 1);
       assert (cy == 0);