shell32: try to guess the working directory in the run dialog

[Juan Lang]

Oops, sorry Vincent, James caught me:

> +    result = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY,
> sizeof(WCHAR)*strlenW(cmdline));

The HEAP_ZERO_MEMORY is the something obvious I was missing.

/me slinks back to his corner.
--Juan