wpa_supplicant: Make GAS Address3 field selection behavior configurable

wpa_supplicant: Make GAS Address3 field selection behavior configurable

IEEE Std 802.11-2012, 10.19 (Public Action frame addressing) specifies
that the wildcard BSSID value is used in Public Action frames that are
transmitted to a STA that is not a member of the same BSS.
wpa_supplicant used to use the actual BSSID value for all such frames
regardless of whether the destination STA is a member of the BSS.

P2P does not follow this rule, so P2P Public Action frame construction
must not be changed. However, the cases using GAS/ANQP for non-P2P
purposes should follow the standard requirements.

Unfortunately, there are deployed AP implementations that do not reply
to a GAS request sent using the wildcard BSSID value. The previously
used behavior (Address3 = AP BSSID even when not associated) continues
to be the default, but the IEEE 802.11 standard compliant addressing
behavior can now be configured with gas_address3=1.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>