VERIFY_CHECK precondition for secp256k1_fe_set_int.

src/field_10x26_impl.h

@@ -264,6 +264,7 @@ static int secp256k1_fe_normalizes_to_zero_var(const secp256k1_fe *r) {
 }
 
 SECP256K1_INLINE static void secp256k1_fe_set_int(secp256k1_fe *r, int a) {
+    VERIFY_CHECK(0 <= a && a <= 0x7FFF);
     r->n[0] = a;
     r->n[1] = r->n[2] = r->n[3] = r->n[4] = r->n[5] = r->n[6] = r->n[7] = r->n[8] = r->n[9] = 0;
 #ifdef VERIFY