Merge bitcoin#16225: tests: Make coins_tests/updatecoins_simulation_t…

…est deterministic

f899580 tests: Make coins_tests/updatecoins_simulation_test deterministic (practicalswift)

Pull request description:

  Make `coins_tests/updatecoins_simulation_test` deterministic.

  Before:

  ```
  $ contrib/devtools/test_deterministic_coverage.sh 1000
  [2019-06-15 05:36:20] Measuring coverage, run #1 of 1000
  [2019-06-15 05:38:05] Measuring coverage, run #2 of 1000
  [2019-06-15 05:39:49] Measuring coverage, run #3 of 1000
  [2019-06-15 05:41:38] Measuring coverage, run #4 of 1000
  [2019-06-15 05:43:16] Measuring coverage, run litecoin-project#5 of 1000
  ...
  [2019-06-16 18:25:23] Measuring coverage, run litecoin-project#880 of 1000
  [2019-06-16 18:27:12] Measuring coverage, run litecoin-project#881 of 1000
  [2019-06-16 18:29:33] Measuring coverage, run litecoin-project#882 of 1000
  [2019-06-16 18:33:00] Measuring coverage, run litecoin-project#883 of 1000
  [2019-06-16 18:35:32] Measuring coverage, run litecoin-project#884 of 1000

  The line coverage is non-deterministic between runs. Exiting.

  The test suite must be deterministic in the sense that the set of lines executed at least
  once must be identical between runs. This is a necessary condition for meaningful
  coverage measuring.

  --- gcovr.run-1.txt     2019-06-15 05:38:05.282359029 +0200
  +++ gcovr.run-884.txt   2019-06-16 18:37:23.518298374 +0200
  @@ -269,7 +269,7 @@
   test/bloom_tests.cpp                         320     320   100%
   test/bswap_tests.cpp                          13      13   100%
   test/checkqueue_tests.cpp                    223     222    99%   169
  -test/coins_tests.cpp                         478     472    98%   52,68,344-345,511,524
  +test/coins_tests.cpp                         478     474    99%   52,68,511,524
   test/compilerbug_tests.cpp                    18      18   100%
   test/compress_tests.cpp                       27      27   100%
   test/crypto_tests.cpp                        268     268   100%
  @@ -401,5 +401,5 @@
   zmq/zmqpublishnotifier.h                       5       0     0%   12,31,37,43,49
   zmq/zmqrpc.cpp                                23       3    13%   16,18,20,23,33-35,37,40-47,51,62,64-65
   ------------------------------------------------------------------------------
  -TOTAL                                      53323   28305    53%
  +TOTAL                                      53323   28307    53%
   ------------------------------------------------------------------------------
  ```

  After:

  ```
  $ contrib/devtools/test_deterministic_coverage.sh 1000
  [2019-06-15 05:36:20] Measuring coverage, run #1 of 1000
  [2019-06-15 05:38:05] Measuring coverage, run #2 of 1000
  [2019-06-15 05:39:49] Measuring coverage, run #3 of 1000
  [2019-06-15 05:41:38] Measuring coverage, run #4 of 1000
  [2019-06-15 05:43:16] Measuring coverage, run litecoin-project#5 of 1000
  ...
  $
  ```

ACKs for commit f89958:
  MarcoFalke:
    ACK f899580 (checked that the randomness state of g_insecure_rand_ctx is the same after three test runs)

Tree-SHA512: 796d362b050c5750e351de1126b62f0f2c8e2d712cf01b6e1a3e2cc6ef92fa68439a32fc24c76d34bce4d553aee4ae4ea88a036c56eb9e25979649a19c59c3e5

src/test/coins_tests.cpp

@@ -278,6 +278,7 @@ UtxoData::iterator FindRandomFrom(const std::set<COutPoint> &utxoSet) {
 BOOST_AUTO_TEST_CASE(updatecoins_simulation_test)
 {
     SeedInsecureRand(/* deterministic */ true);
+    g_mock_deterministic_tests = true;
 
     bool spent_a_duplicate_coinbase = false;
     // A simple map to track what we expect the cache stack to represent.
@@ -472,6 +473,8 @@ BOOST_AUTO_TEST_CASE(updatecoins_simulation_test)
 
     // Verify coverage.
     BOOST_CHECK(spent_a_duplicate_coinbase);
+
+    g_mock_deterministic_tests = false;
 }
 
 BOOST_AUTO_TEST_CASE(ccoins_serialization)