test: escape script filename on Windows

Escape backslashes in script filename on Windows in a CLI test.

PR-URL: #16124
Fixes: #16057 and #16023
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-cli-eval.js

@@ -118,7 +118,10 @@ child.exec(`${nodejs} --use-strict -p process.execArgv`,
 
 // Regression test for https://github.com/nodejs/node/issues/3574.
 {
-  const emptyFile = fixtures.path('empty.js');
+  let emptyFile = fixtures.path('empty.js');
+  if (common.isWindows) {
+    emptyFile = emptyFile.replace(/\\/g, '\\\\');
+  }
 
   child.exec(`${nodejs} -e 'require("child_process").fork("${emptyFile}")'`,
              common.mustCall((err, stdout, stderr) => {