package/minidlna: disable broken toolchains on nios2

minidlna triggers the _gp bug:
http://article.gmane.org/gmane.comp.lib.uclibc.buildroot/77875/

Fixes
http://autobuild.buildroot.net/results/712/71230ee530a41b3611cd4526f0f010f9c2ef25eb/
http://autobuild.buildroot.net/results/79c/79cbae4dab3ad712bc20c752fdd91e168eade9fe/
http://autobuild.buildroot.net/results/df7/df7da91985a7bf2b05093bae7379ef22362a44fc/


and many others

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>