child_process: remove lookup of undefined property

execSync() passes opts.args to checkExecSyncError(). There are
two problems:

1. opts.args appears to always be undefined.
2. Even if it was defined, checkExecSyncError() would not use
   it since the command input is guaranteed to be defined.

This commit updates the code to pass undefined instead.

lib/child_process.js

@@ -940,7 +940,7 @@ function execSync(command, options) {
   if (inheritStderr && ret.stderr)
     process.stderr.write(ret.stderr);
 
-  const err = checkExecSyncError(ret, opts.args, command);
+  const err = checkExecSyncError(ret, undefined, command);
 
   if (err)
     throw err;