hostapd: make country3 option configurable

hostapd: make country3 option configurable

The country3 option in hostapd.conf allows the third octet of the country
string to be set. It can be used e.g. to indicate indoor or outdoor use (see
hostapd.conf for further details). Make this option configurable but optional
in OpenWrt.

Signed-off-by: Timo Sigurdsson <public_timo.s@silentcreek.de>
[bump PKG_RELEASE, rebase]
Signed-off-by: Paul Spooren <mail@aparcar.org>
(cherry picked from commit 9f09c1936a4a13b67fcba632f7ca02331f685359)
Signed-off-by: Paul Spooren <mail@aparcar.org>