core: use compare and swap in ring

Link: https://github.com/GeneAssembly/biosal/issues/763
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: pull more than 1 message per iteration

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
tracepoints:  add LTTng tracepoints for actor

Link: https://github.com/GeneAssembly/biosal/issues/762
Link: https://github.com/GeneAssembly/biosal/issues/764
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>