[PATCH v6] Cygwin: rewrite cmdline parser

[Mingye Wang]

Oh, I should also mention that this patch does *not* fix globbing with 
Windows paths. Although stuff like (in node-js):

     child_process.spawnSync("C:\\cygwin64\\bin\\echo.exe", 
["C:\\Qt\\*"], {encoding: 'utf-8'})

is correctly fed to glob(3), the glob() function does not perform any 
interpretation of Windows paths.  The older parser have the same 
behavior and I didn't change that, seeing there are two ways this can 
play out:

* Cygwin goes to extend glob() with the ability to do Windows paths
   under a new flag.  Globify() is modified to use that flag too.
* Cygwin does not extend glob(), so globify() is modified to skip on
   is_dos_path much like how it already skips with a strpbrk.

Regards,
Artoria2e5