qt: broken on avr32

Qt is broken for the avr32 architecture since it lacks TLS support.
Fixes:
http://autobuild.buildroot.net/results/56d/56d1d8f12a847f1ba49547a51d7a3605755a0bb8/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>