Move the shared IEEE 802.11w enum definition into src/common/defs.h to
avoid redefinition when both configuration structures are included into
the same file.
This version is adding the configuration option (mode=2) for this and
driver capability reporting to figure out whether AP mode can be used.
However, this does not actually implement any real functionality yet.
Added a new configuration option, wpa_ptk_rekey, that can be used to
enforce frequent PTK rekeying, e.g., to mitigate some attacks against TKIP
deficiencies. This can be set either by the Authenticator (to initiate
periodic 4-way handshake to rekey PTK) or by the Supplicant (to request
Authenticator to rekey PTK).
With both wpa_ptk_rekey and wpa_group_rekey (in hostapd) set to 600, TKIP
keys will not be used for more than 10 minutes which may make some attacks
against TKIP more difficult to implement.
