cleanup: Remove faulty env processing functions

cleanup: Remove faulty env processing functions

The env_set_add_to_environmenti() and env_set_remove_from_environment()
functions where not used in the code at all and they would cause an
ASSERT() in setenv_str_ex() later on, as it would not allow the
struct env_set *es pointer to be NULL (misc.c:807).

Signed-off-by: David Sommerseth <davids@openvpn.net>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20170225020229.17287-1-davids@openvpn.net>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg14195.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>