package/bluez_utils: fix test build issues with musl

Add one missing header and avoid encrypt redefinition.

Fixes:
http://autobuild.buildroot.net/results/06c/06c930d9c5299b79500d018ac3fb2861ce834c7c/



Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>