C++17 support (#4482)

Summary:
Closes https://github.com/facebook/rocksdb/issues/4462

I'm not sure if you'll be happy with `std::random_device{}`, perhaps you would want to use your rand instance instead. I didn't test to see if your rand instance supports the requirements that `std::shuffle` takes.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4482

Differential Revision: D10325133

Pulled By: yiwu-arbug

fbshipit-source-id: 47b7adaf4bb2b8d64cf090ea6b1b48ef53180581

util/transaction_test_util.cc

@@ -13,6 +13,7 @@
 #include <inttypes.h>
 #include <algorithm>
 #include <numeric>
+#include <random>
 #include <string>
 #include <thread>
 
@@ -135,8 +136,7 @@ bool RandomTransactionInserter::DoInsert(DB* db, Transaction* txn,
 
   std::vector<uint16_t> set_vec(num_sets_);
   std::iota(set_vec.begin(), set_vec.end(), static_cast<uint16_t>(0));
-  std::random_shuffle(set_vec.begin(), set_vec.end(),
-                      [&](uint64_t r) { return rand_->Uniform(r); });
+  std::shuffle(set_vec.begin(), set_vec.end(), std::random_device{});
 
   // For each set, pick a key at random and increment it
   for (uint16_t set_i : set_vec) {
@@ -258,10 +258,8 @@ Status RandomTransactionInserter::Verify(DB* db, uint16_t num_sets,
 
   std::vector<uint16_t> set_vec(num_sets);
   std::iota(set_vec.begin(), set_vec.end(), static_cast<uint16_t>(0));
-  if (rand) {
-    std::random_shuffle(set_vec.begin(), set_vec.end(),
-                        [&](uint64_t r) { return rand->Uniform(r); });
-  }
+  std::shuffle(set_vec.begin(), set_vec.end(), std::random_device{});
+
   // For each set of keys with the same prefix, sum all the values
   for (uint16_t set_i : set_vec) {
     // Five digits (since the largest uint16_t is 65535) plus the NUL