Fix: cleanup configure.ac and add missing headers/functions

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
[HEAD MERGE] working version with fork(). no resize

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
[MERGE] more fixes. Cleanup code

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
[MERGE] close shm fd at pool destroy

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
[MERGE] fix add / for portability

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
[MERGE] Fix: update configure.ac with shm_open lib lookup

Signed-off-by: David Goulet <dgoulet@ev0ke.net>