api: configurable binary api client rx pthread fcn

api: configurable binary api client rx pthread fcn

Add vl_client_connect_to_vlib_thread_fn (...) and export the
memory_client_main_t definition.

If you use this new API, make sure not to miss the setjmp / longjmp
dance shown in .../src/vlibmemory/memory_client.c:rx_thread_fn(...),
which is required for the rx pthread to terminate cleanly; please
process client delete reply messages in the rx thread...

Type: refactor

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: Ia67038ec59e2e14b174c67afca15b2c3f67a4d20
(cherry picked from commit 920180e5e0722c78c258ff26476fd5efa434032d)