ck_rhs: Add.

Introduce ck_rhs, a variant of ck_hs that uses the robin hood algorithm for
insertion, and backward shift delete for deletion.
ck_rhs: Increase CK_RHS_G from 2 to 1024, since it's used a lot more.
ck_hrs: Update probe_bound for every slot shifted.

In ck_rhs_do_backward_shift_delete(), find if any entry with the same hash
is stored further, and if not, update probe_bound for every entry being
shifted, instead of just doing it for the slot being emptied.
ck_rhs: Add a read mostly mode.

Add a read-mostly mode, in which entries won't share cache lines with
associated datas (probes, probe_bound, etc).
This makes write operations slower, but make get faster.
ck_rhs: remove debugging printfs
ck_rhs: Various clean-up.
ck_rhs: Move probe function to right namespace.

Sleep deprivation...
ck_rhs: Remove unnecessary parentheses.
ck_rhs: Additional clean-up.
ck_rhs: Use inlined functions instead of gruesome macros.
ck_rhs: style(9)
build: Support customizable library names.

This is primarily for Mac OS X at the moment, but may come
in handy for other targets in the future.
build: Bump feature version in preparation.
Merge remote-tracking branch 'origin/cognet'
regressions: Add ck_rhs to top-level Makefile.