error: De-duplicate code creating Error objects Duplicated when commit 680d16d added error_set_errno(), and again when commit 20840d4 added error_set_win32(). Make the original copy in error_set() reusable by factoring out error_setv(), then rewrite error_set_errno() and error_set_win32() on top of it. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>