Use new RNG and tinytest code to simplify prob_distr tests

Since the reproducible RNG dumps its own seed, we don't need to do
it for it. Since tinytest can tell us if the test failed, we don't
need our own test_failed booleans.

src/test/test_prob_distr.c

@@ -1119,13 +1119,14 @@ test_psi_dist_sample(const struct dist *dist)
 }
 
 static void
-dump_seed(void)
+write_stochastic_warning(void)
 {
-  printf("\n"
+  if (tinytest_cur_test_has_failed()) {
+    printf("\n"
          "NOTE: This is a stochastic test, and we expect it to fail from\n"
          "time to time, with some low probability. If you see it fail more\n"
          "than one trial in 100, though, please tell us.\n\n");
-  testing_dump_reproducible_rng_seed();
+  }
 }
 
 static void
@@ -1180,7 +1181,7 @@ test_stochastic_uniform(void *arg)
 
  done:
   if (tests_failed) {
-    dump_seed();
+    write_stochastic_warning();
   }
   testing_disable_reproducible_rng();
 }
@@ -1273,7 +1274,7 @@ test_stochastic_genpareto(void *arg)
 
  done:
   if (tests_failed) {
-    dump_seed();
+    write_stochastic_warning();
   }
   testing_disable_reproducible_rng();
 }
@@ -1301,7 +1302,7 @@ test_stochastic_geometric(void *arg)
 
  done:
   if (tests_failed) {
-    dump_seed();
+    write_stochastic_warning();
   }
   testing_disable_reproducible_rng();
 }
@@ -1328,7 +1329,7 @@ test_stochastic_logistic(void *arg)
 
  done:
   if (tests_failed) {
-    dump_seed();
+    write_stochastic_warning();
   }
   testing_disable_reproducible_rng();
 }
@@ -1337,7 +1338,6 @@ static void
 test_stochastic_log_logistic(void *arg)
 {
   bool ok = 0;
-  bool tests_failed = true;
   (void) arg;
 
   testing_enable_reproducible_rng();
@@ -1351,12 +1351,8 @@ test_stochastic_log_logistic(void *arg)
   ok = test_stochastic_log_logistic_impl(exp(-10), 1e-2);
   tt_assert(ok);
 
-  tests_failed = false;
-
  done:
-  if (tests_failed) {
-    dump_seed();
-  }
+  write_stochastic_warning();
   testing_disable_reproducible_rng();
 }
 
@@ -1364,7 +1360,6 @@ static void
 test_stochastic_weibull(void *arg)
 {
   bool ok = 0;
-  bool tests_failed = true;
   (void) arg;
 
   testing_enable_reproducible_rng();
@@ -1380,12 +1375,8 @@ test_stochastic_weibull(void *arg)
   ok = test_stochastic_weibull_impl(10, 1);
   tt_assert(ok);
 
-  tests_failed = false;
-
  done:
-  if (tests_failed) {
-    dump_seed();
-  }
+  write_stochastic_warning();
   testing_disable_reproducible_rng();
   UNMOCK(crypto_rand);
 }