Configure kleopatra with different organization names

* src/gpg4win.mk.in (KLEOPATRA_ORGANIZATION_NAME): New.
* src/Makefile.am (gpg4win_pkg_kleopatra_configure): Add
-DKLEOPATRA_ORGANIZATION_NAME option.

The organization name (and the application name) is used in the
Windows registry path to look up settings.

• GnuPG-bug-id: T5707