grit: delay "help" builtin parsing

The "help" ad-hoc parsing only works in the simplest case:
  grit help
  grit help foo

When passing options to grit, the "help" builtin fails and producing
confusing output:
  $ grit -i ... help
  No such tool.  Try running 'grit help' for a list of tools.
  $ grit -i ... help xmb
  No such tool.  Try running 'grit help' for a list of tools.

Delay parsing of the "help" tool until after we've processed grit's
core options.

Bug: 747171
Change-Id: Iae5fdee2493346cee4272368ac8862647433faaf
Reviewed-on: https://chromium-review.googlesource.com/c/1320690Reviewed-by: agrieve <agrieve@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605854}

tools/grit/grit/grit_runner.py

@@ -196,20 +196,6 @@ def Main(args):
   """Parses arguments and does the appropriate thing."""
   util.ChangeStdoutEncoding()
 
-  if not args or (len(args) == 1 and args[0] == 'help'):
-    PrintUsage()
-    return 0
-  elif len(args) == 2 and args[0] == 'help':
-    tool = args[1].lower()
-    if not _GetToolInfo(tool):
-      print "No such tool.  Try running 'grit help' for a list of tools."
-      return 2
-
-    print ("Help for 'grit %s' (for general help, run 'grit help'):\n"
-           % (tool))
-    print _GetToolInfo(tool)[_FACTORY]().__doc__
-    return 0
-  else:
   options = Options()
   try:
     args = options.ReadOptions(args)  # args may be shorter after this
@@ -220,7 +206,22 @@ def Main(args):
   if not args:
     print "No tool provided.  Try running 'grit help' for a list of tools."
     return 2
+
   tool = args[0]
+  if tool == 'help':
+    if len(args) == 1:
+      PrintUsage()
+      return 0
+    else:
+      tool = args[1]
+      if not _GetToolInfo(tool):
+        print "No such tool.  Try running 'grit help' for a list of tools."
+        return 2
+
+      print ("Help for 'grit %s' (for general help, run 'grit help'):\n"
+             % (tool))
+      print _GetToolInfo(tool)[_FACTORY]().__doc__
+      return 0
   if not _GetToolInfo(tool):
     print "No such tool.  Try running 'grit help' for a list of tools."
     return 2