Compilation regression

[Jonathan Bither]

I just noticed that I am no longer able to compile hostapd on my CentOS6 
system since commit 97ed9a06df566357f0ebe57f8080f78726e78db6.

../src/drivers/driver_nl80211.c: In function ‘wpa_driver_nl80211_deinit’:
../src/drivers/driver_nl80211.c:4941: warning: implicit declaration of 
function ‘nl_socket_free’

../src/drivers/driver_nl80211.o: In function `wpa_driver_nl80211_deinit':
/home/jonathan/hostap/hostapd/../src/drivers/driver_nl80211.c:4941: 
undefined reference to `nl_socket_free'
collect2: ld returned 1 exit status
make: *** [hostapd] Error 1