Add SME support (separate authentication and association)

This can be used, e.g., with mac80211-based Linux drivers with
nl80211. This allows over-the-air FT protocol to be used (IEEE
802.11r).

Since the nl80211 interface needed for this is very recent (added
today  into wireless-testing.git), driver_nl80211.c has backwards
compatibility code that uses WEXT for association if the kernel does
not support the new commands. This compatibility code can be
disabled by defining NO_WEXT_COMPAT. That code will also be removed
at  some point to clean up driver_nl80211.c.

src/common/defs.h

@@ -128,6 +128,16 @@ typedef enum {
 	 */
 	WPA_SCANNING,
 
+	/**
+	 * WPA_AUTHENTICATING - Trying to authenticate with a BSS/SSID
+	 *
+	 * This state is entered when wpa_supplicant has found a suitable BSS
+	 * to authenticate with and the driver is configured to try to
+	 * authenticate with this BSS. This state is used only with drivers
+	 * that use wpa_supplicant as the SME.
+	 */
+	WPA_AUTHENTICATING,
+
 	/**
 	 * WPA_ASSOCIATING - Trying to associate with a BSS/SSID
 	 *