On Windows the feature of `INEXTRA` doesn't work because it needs handling of inherited HANDLEs from parent process.
In gnupg master, inherited HANDLE is supported, so, it will be possible to support the feature correctly.
This will improve the cases:
- wks-client / wks-server (`verify_signature` function invoking gpg with `INEXTRA`, in wks-receive.c)
- dirmngr for SWDB