thorium_node: use static keyword in C file

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: use a macro in upper case for fences

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
core: use inline keyword for memory fences

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>