package/bluez_utils: fix musl compilation issue

http://autobuild.buildroot.net/results/4e4/4e4cea0234e6abf5882296abd5ceeda6ccab89b0/



Signed-off-by: Brendan Heading <brendanheading@gmail.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Tested-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>