Fix printf formatting on MacOS (#4533)

Summary:
On MacOS with clang the compilation of _tools/db_bench_tool.cc_ always fails because the format used in a `fprintf` call has the wrong type. This PR should hopefully fix this issue
```
tools/db_bench_tool.cc:4233:61: error: format specifies type 'unsigned long long' but the argument has type 'size_t' (aka 'unsigned long')
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4533

Differential Revision: D10471657

Pulled By: maysamyabandeh

fbshipit-source-id: f20f5f3756d3571b586c895c845d0d4d1e34a398

.travis.yml

@@ -90,7 +90,7 @@ script:
       OPT=-DTRAVIS V=1 ROCKSDBTESTS_START=db_block_cache_test ROCKSDBTESTS_END=full_filter_block_test make -j4 check_some
       ;;
     2)
-      OPT=-DTRAVIS V=1 ROCKSDBTESTS_START=full_filter_block_test ROCKSDBTESTS_END=write_batch_with_index_test make -j4 check_some
+      OPT=-DTRAVIS V=1 make -j4 tools && OPT=-DTRAVIS V=1 ROCKSDBTESTS_START=full_filter_block_test ROCKSDBTESTS_END=write_batch_with_index_test make -j4 check_some
       ;;
     3)
       OPT=-DTRAVIS V=1 ROCKSDBTESTS_START=write_batch_with_index_test ROCKSDBTESTS_END=write_prepared_transaction_test make -j4 check_some

tools/db_bench_tool.cc

@@ -4237,7 +4237,7 @@ void VerifyDBFromDB(std::string& truth_db_name) {
         }
         if (levelMeta.level == 0) {
           for (auto& fileMeta : levelMeta.files) {
-            fprintf(stdout, "Level[%d]: %s(size: %" PRIu64 " bytes)\n",
+            fprintf(stdout, "Level[%d]: %s(size: %" ROCKSDB_PRIszt " bytes)\n",
                     levelMeta.level, fileMeta.name.c_str(), fileMeta.size);
           }
         } else {