package/kodi-pvr-mediaportal-tvserver: Fix compile error with gcc5

Fixes
http://autobuild.buildroot.net/results/651/651c47c611f0eaa317acb338d609d8851ea7b463/
http://autobuild.buildroot.net/results/63e/63edc869b780e387a8e94334bbe52ffa1c2a5f85/



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>