[PATCH] SMP SSL session cache implementation

This patch implement SSL session cache sharing across SMP workers using
shared memory. The following new squid configuration options added:

 - The "sslproxy_session_cache_size" option which sets the cache size to
use for ssl session. Example usage:
     sslproxy_session_cache_size 4 MB

 - The "sslproxy_session_ttl" option which defines the time in seconds
the ssl session is valid. Example usage:
     sslproxy_session_ttl 600

This patch also investigates the Ipc::MemMap class to help squid
developers implement shared caches for squid processes.

This is a Measurement Factory project