[Bug 21338] cmd needs to set COMSPEC, PATHEXT, and PROMPT environment variables on startup

http://bugs.winehq.org/show_bug.cgi?id=21338

--- Comment #7 from Dima Ryazanov   2010-01-12 10:14:20 ---
Created an attachment (id=25697)
 --> (http://bugs.winehq.org/attachment.cgi?id=25697)
Patch

It's a little redundant, but I'm not sure what's the best way to fix that:
- WCMD_show_prompt sets a default PROMPT if it's missing - but this isn't
needed anymore. However, the user could theoretically make PROMPT longer than
MAX_PATH, so this case still needs to be handled.
- WCMD_run_program sets a default PATHEXT, same as above.