Remove runtime dependency on liburcu shared objects

Remove the runtime dependency on:

- liblurcu-bp.so
- liblurcu-cds.so
- compat futex code.

By integrating those into the lttng-ust project.

For rculfhash, only the minimum pieces needed by lttng-ust are
integrated (no auto-resize, no accounting).

lttng-ust still requires liburcu at build time for header dependencies.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Idffb205b27b1bb0f972523c3ce3bdaf25bfe1710