package/tyrian: fixes compilation with static libs

Has been tested with: "./support/scripts/test-pkg -c tyrian.cfg -p opentyrian"
Fixes: http://autobuild.buildroot.net/results/0e2345db82b33f591958fc0f72ad914adafe0522


and some similar previous build failure.

Thanks Thomas for the tip ;-).

Signed-off-by: Julien BOIBESSOT <julien.boibessot@armadeus.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>