package/tvheadend: needs dynamic libraries

Fixes
http://autobuild.buildroot.net/results/f1c/f1c40ac9dda5ceeb5665d021333058eb29828d62/
http://autobuild.buildroot.net/results/bd0/bd0e8619df7cd8f21da96ae470691b1ebb2f156c/
http://autobuild.buildroot.net/results/f1c/f1c40ac9dda5ceeb5665d021333058eb29828d62/



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>