Adds benchmark for Concurrency Kit.
Restores the google libchash, even if still disabled.
Merge branch 'ck'

Conflicts:
	benchmark.cc
	benchmark/gr_def_random_change.gnu
	benchmark/gr_def_random_hit.gnu
	benchmark/gr_forward_change.gnu
	benchmark/gr_forward_hit.gnu
	benchmark/gr_forward_insert.gnu
	benchmark/gr_forward_miss.gnu
	benchmark/gr_forward_remove.gnu
	benchmark/gr_forward_size.gnu
	benchmark/gr_other_cgoogledensehash_problem.gnu
	benchmark/gr_other_judy_problem.gnu
	benchmark/gr_random_change.gnu
	benchmark/gr_random_hit.gnu
	benchmark/gr_random_insert.gnu
	benchmark/gr_random_miss.gnu
	benchmark/gr_random_remove.gnu
	benchmark/gr_random_size.gnu
Adds tests for ck and libchash.