liblttng-ust-fd doesn't use the internal logging system

liblttng-ust-fd doesn't use the internal logging system

liblttng-ust-fd is a standalone library that only uses liblttng-ust
public symbols and doesn't currently use the internal logging system. We
don't need to link against the private convenience library and
initialize the logging system, clean this up.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ifd111722e4034de70f68adc3c84b466e3d490370