[cctest] adding --help option to output basic information about cctest

tools/testrunner/local/commands.py

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 43 matching lines @@
   popen_args = args
   prev_error_mode = SEM_INVALID_VALUE
   if utils.IsWindows():
     popen_args = subprocess.list2cmdline(args)
     # Try to change the error mode to avoid dialogs on fatal errors. Don't
     # touch any existing error mode flags by merging the existing error mode.
     # See http://blogs.msdn.com/oldnewthing/archive/2004/07/27/198410.aspx.
     error_mode = SEM_NOGPFAULTERRORBOX
     prev_error_mode = Win32SetErrorMode(error_mode)
     Win32SetErrorMode(error_mode | prev_error_mode)
-  process = subprocess.Popen(
-    args=popen_args,
-    stdout=subprocess.PIPE,
-    stderr=subprocess.PIPE,
-    **rest
-  )
+
+  try:
+    process = subprocess.Popen(
+      args=popen_args,
+      stdout=subprocess.PIPE,
+      stderr=subprocess.PIPE,
+      **rest
+    )
+  except Exception as e:
+    sys.stderr.write("Error executing: %s\n" % popen_args)
+    raise e
+
   if (utils.IsWindows() and prev_error_mode != SEM_INVALID_VALUE):
     Win32SetErrorMode(prev_error_mode)
 
   def kill_process(process, timeout_result):
     timeout_result[0] = True
     try:
       if utils.IsWindows():
         if verbose:
           print "Attempting to kill process %d" % process.pid
           sys.stdout.flush()
@@ skipping 25 matching lines @@
 
 
 def Execute(args, verbose=False, timeout=None):
   args = [ c for c in args if c != "" ]
   exit_code, timed_out, stdout, stderr = RunProcess(
     verbose,
     timeout,
     args=args,
   )
   return output.Output(exit_code, timed_out, stdout, stderr)