test: fix test/pummel/test-fs-largefile.js

test-fs-largefile.js calls `fs.close()` without a callback which results
in an error as of Node.js 10.0.0. Add a `common.mustCall()` callback so
the test passes again.

PR-URL: nodejs#25372
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

test/pummel/test-fs-largefile.js

@@ -20,7 +20,7 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 'use strict';
-require('../common');
+const common = require('../common');
 
 const assert = require('assert');
 const fs = require('fs');
@@ -46,7 +46,7 @@ assert.strictEqual(readBuf[0], 0);
 
 // Verify that floating point positions do not throw.
 fs.writeSync(fd, writeBuf, 0, writeBuf.length, 42.000001);
-fs.close(fd);
+fs.close(fd, common.mustCall());
 
 // Normally, we don't clean up tmp files at the end of a test, but we'll make an
 // exception for a 5 GB file.