bluez_utils: broken for static builds

The bluez_utils package requires shared library support unconditionally.
We can't fix it to make it build on static because, for instance,
"plugin.c" file uses dlfcn and it's a basic prereq for bluetoothd, so
add "depend on !BR2_PREFER_STATIC_LIB" to it and recursively to all
packages that selects BR2_PACKAGE_BLUEZ_UTILS.

Fixes:

   http://autobuild.buildroot.net/results/d81/d81970024649c1e89c01da491c63760afdad6cb6/



Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>