bluez5_utils: not for static builds

Disable for static builds, it uses dlfcn. Fixes:
http://autobuild.buildroot.net/results/7cd/7cd87c9e9b8b41ee01413050e554b5422d207e70/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Reviewed-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>