Subzero: Correct the cross test's diagnostic message for a test failure.

pydir/crosstest_generator.py

 #!/usr/bin/env python2
 
 import argparse
 import ConfigParser
 import os
 import shutil
 import sys
 
 from utils import shellcmd
 from utils import FindBaseNaCl
@@ skipping 158 matching lines @@
               else:
                 run_cmd = RunNativePrefix(args.toolchain_root, target, run_cmd)
               if args.lit:
                 # Create a file to drive the lit test.
                 with open(run_cmd_base + '.xtest', 'w') as f:
                   f.write('# RUN: sh %s | FileCheck %s\n')
                   f.write('cd ' + crosstest_dir + ' && \\\n')
                   f.write(' '.join(cmp_cmd) + ' && \\\n')
                   f.write(run_cmd + '\n')
                   f.write('echo Recreate a failure using ' + __file__ +
+                          ' --toolchain-root=' + args.toolchain_root +
                           ' --include=' + ','.join(desc) + '\n')
                   f.write('# CHECK: Failures=0\n')
               else:
                 if not args.no_compile:
                   shellcmd(cmp_cmd,
                            echo=args.verbose)
                 if (args.defer):
                   deferred_cmds.append(run_cmd)
                 else:
                   shellcmd(run_cmd, echo=True)
   for run_cmd in deferred_cmds:
     shellcmd(run_cmd, echo=True)
 
 if __name__ == '__main__':
   main()