Merge bitcoin#759: Fix uninitialized variables in ecmult_multi test

2e7fc5b Fix uninitialized variables in ecmult_multi test (Jonas Nick)

Pull request description:

  Fixes bitcoin#756

ACKs for top commit:
  real-or-random:
    ACK 2e7fc5b I inspected the diff. I did not test it and I did not check whether if makes the warning go away
  elichai:
    tACK 2e7fc5b

Tree-SHA512: 674400134f5487236f5b6e8b3020b346d43662511628cdf6dd1bd7ba1de985bf93f5be11f5650f250ff37b5f87eb4b01d90ed53d41193c05a420d3f5a2d63470

Author: real-or-random

src/tests.c

@@ -2967,14 +2967,16 @@ void test_ecmult_multi(secp256k1_scratch *scratch, secp256k1_ecmult_multi_func e
 
 void test_ecmult_multi_batch_single(secp256k1_ecmult_multi_func ecmult_multi) {
     secp256k1_scalar szero;
-    secp256k1_scalar sc[32];
-    secp256k1_ge pt[32];
+    secp256k1_scalar sc;
+    secp256k1_ge pt;
     secp256k1_gej r;
     ecmult_multi_data data;
     secp256k1_scratch *scratch_empty;
 
-    data.sc = sc;
-    data.pt = pt;
+    random_group_element_test(&pt);
+    random_scalar_order(&sc);
+    data.sc = ≻
+    data.pt = &pt;
     secp256k1_scalar_set_int(&szero, 0);
 
     /* Try to multiply 1 point, but scratch space is empty.*/