test: skip long path tests on non-Windows

If not running on Windows it skips the long path tests in:

* test-fs-long-path.js
* test-require-long-path.js

Fixes: #2255
PR-URL: #4116
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Minwoo Jung <jmwsoft@gmail.com>

test/parallel/test-fs-long-path.js

@@ -4,6 +4,11 @@ var fs = require('fs');
 var path = require('path');
 var assert = require('assert');
 
+if (!common.isWindows) {
+  console.log('1..0 # Skipped: this test is Windows-specific.');
+  return;
+}
+
 var successes = 0;
 
 // make a path that will be at least 260 chars long.

test/parallel/test-require-long-path.js

@@ -3,6 +3,11 @@ const common = require('../common');
 const fs = require('fs');
 const path = require('path');
 
+if (!common.isWindows) {
+  console.log('1..0 # Skipped: this test is Windows-specific.');
+  return;
+}
+
 // make a path that is more than 260 chars long.
 const dirNameLen = Math.max(260 - common.tmpDir.length, 1);
 const dirName = path.join(common.tmpDir, 'x'.repeat(dirNameLen));