wpa-supplicant: add 802.11r client support

Add 802.11r client support to wpa_supplicant. It's only enabled in
wpa_supplicant-full. hostapd gained 802.11r support in commit r45051.

Tested on a TP-Link TL-WR710N sta psk client with two 802.11r enabled
openwrt accesspoints (TP-Link TL-WDR3600).

Signed-off-by: Stefan Hellermann <stefan@the2masters.de>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@46377 3c298f89-4303-0410-b956-a3cf2f4a3e73