benchmark: use test/common/tmpdir consistently

Many benchmarks use test/common/tmpdir. This changes 3 benchmarks that use
NODE_TMPDIR to also use test/common/tmpdir.

This is necessary in preparation for the next commit that changes tmpdir to
delete tmpdir.path when the Node.js process exits. Thus, if multiple
benchmarks are run sequentially, the ones that use tmpdir will remove the
directory and the ones changed here would fail because it does not exist.
This happens when running test/benchmark.

Note: to explicitly select a directory for tmpdir, use NODE_TEST_DIR.

benchmark/fs/read-stream-throughput.js

@@ -3,11 +3,14 @@
 
 const path = require('path');
 const common = require('../common.js');
-const filename = path.resolve(process.env.NODE_TMPDIR || __dirname,
-                              `.removeme-benchmark-garbage-${process.pid}`);
 const fs = require('fs');
 const assert = require('assert');
 
+const tmpdir = require('../../test/common/tmpdir');
+tmpdir.refresh();
+const filename = path.resolve(tmpdir.path,
+                              `.removeme-benchmark-garbage-${process.pid}`);
+
 let encodingType, encoding, size, filesize;
 
 const bench = common.createBenchmark(main, {

benchmark/fs/readfile.js

@@ -5,11 +5,14 @@
 
 const path = require('path');
 const common = require('../common.js');
-const filename = path.resolve(process.env.NODE_TMPDIR || __dirname,
-                              `.removeme-benchmark-garbage-${process.pid}`);
 const fs = require('fs');
 const assert = require('assert');
 
+const tmpdir = require('../../test/common/tmpdir');
+tmpdir.refresh();
+const filename = path.resolve(tmpdir.path,
+                              `.removeme-benchmark-garbage-${process.pid}`);
+
 const bench = common.createBenchmark(main, {
   dur: [5],
   len: [1024, 16 * 1024 * 1024],

benchmark/fs/write-stream-throughput.js

@@ -3,10 +3,13 @@
 
 const path = require('path');
 const common = require('../common.js');
-const filename = path.resolve(process.env.NODE_TMPDIR || __dirname,
-                              `.removeme-benchmark-garbage-${process.pid}`);
 const fs = require('fs');
 
+const tmpdir = require('../../test/common/tmpdir');
+tmpdir.refresh();
+const filename = path.resolve(tmpdir.path,
+                              `.removeme-benchmark-garbage-${process.pid}`);
+
 const bench = common.createBenchmark(main, {
   dur: [5],
   encodingType: ['buf', 'asc', 'utf'],

test/benchmark/test-benchmark-fs.js

@@ -19,4 +19,4 @@ runBenchmark('fs', [
   'filesize=1024',
   'dir=.github',
   'withFileTypes=false'
-], { NODE_TMPDIR: tmpdir.path, NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });
+], { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });