dirmngr: Avoid initial delay on the first keyserver access.

* dirmngr/dirmngr.c (dirmngr_never_use_tor_p): New.
* dirmngr/server.c (ensure_keyserver): Don't even test for the Tor
proxy in never-use-tor Mode.
* tools/gpgtar-create.c: Include unistd.h to avoid a warning on
Windows.

This delay of 2 or 3 seconds is in particular annoying on Windows.
This is now suppressed, as it should be, if --no-use-tor is used.

The second patch is unrelated