teamd: make usock enabled by default

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
libteamdctl: get cli structs by function call

Due to use of -fvisibility=hidden getting cli struct by global variable
not always worked correctly. Fix by getting via function call.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
make D-Bus optional at compile time

Signed-off-by: Jiri Pirko <jiri@resnulli.us>