[Bug 18154] cmd.exe: failure to handle file extension association

https://bugs.winehq.org/show_bug.cgi?id=18154

--- Comment #12 from Jason Edmeades  ---
For reference, I dont believe this patch was rejected and at the time was good
to go, but I sent it in a batch of fixes and one earlier in the chain needed
rework so this never got in. Unfortunately I'm not working on linux/wine at the
moment, so cannot rebase, but feel free to resubmit