RT3856: Fix memory leaks in test code

Reviewed-by: Matt Caswell <matt@openssl.org>
diff --git a/test/bntest.c b/test/bntest.c
index 1ce6db1..cf4d2ab 100644
--- a/test/bntest.c
+++ b/test/bntest.c
@@ -1043,7 +1043,6 @@
 int test_mod_exp_mont5(BIO *bp, BN_CTX *ctx)
 {
     BIGNUM *a, *p, *m, *d, *e;
-
     BN_MONT_CTX *mont;
 
     a = BN_new();
@@ -1051,7 +1050,6 @@
     m = BN_new();
     d = BN_new();
     e = BN_new();
-
     mont = BN_MONT_CTX_new();
 
     BN_bntest_rand(m, 1024, 0, 1); /* must be odd for montgomery */
@@ -1100,6 +1098,7 @@
         fprintf(stderr, "Modular exponentiation test failed!\n");
         return 0;
     }
+    BN_MONT_CTX_free(mont);
     BN_free(a);
     BN_free(p);
     BN_free(m);