Fix: Remove dependency to urcu-cds in tools tests

The -lurcu-cds link flag is not mandatory to link any of the tests.
Also, adding this flag can cause multiple symbol definition errors when
linking statically because the libhashtable contains symbol names that
are also present in urcu-cds.

Signed-off-by: Christian Babeux <christian.babeux@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>