Problem: Windows: Vim always adds the current directory to search path.
This should only happen when using cmd.exe as 'shell'. For
example, powershell won't run binaries from the current
directory.
Solution: Only add current directory to system path, when using cmd.exe
as 'shell'.
related: vim/vim#10341
related: 083ec6d9a3b7
4d87c9742a
Co-authored-by: Christian Brabandt <cb@256bit.org>