fix: use urcu-tls compat with c++ compiler

fix: use urcu-tls compat with c++ compiler

  * Initialize all fields of 'struct urcu_tls' to avoid :

    sorry, unimplemented: non-trivial designated initializers not supported

  * Cast void* to proper type pointers to avoid :

    error: invalid conversion from ‘void*’ to ...

Change-Id: I654f924324cda2eaea723f4a0759d706b2a2bf40
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>