Merge: 6fb5e9636fa1fffc62e86561e7dcd734fa2ee53f
Add defer_accept option to enable TCP_DEFER_ACCEPT
Charybdis commits referenced:
atheme/charybdis@77cb59b
libratbox: add support for TCP_DEFER_ACCEPT on linux
atheme/charybdis@aa4737a
libratbox: make defer_accept optional.
atheme/charybdis@02270e9
Add listen::defer_accept option for controlling usage
of TCP_DEFER_ACCEPT option.
atheme/charybdis@797a29f
libratbox: Allow defer_accept on FreeBSD.
Use RB_SOCKADDR_HAS_SA_LEN instead of SOCKADDR_IN_HAS_LEN
which is only defined inside libratbox.
This fixes creating own sockaddr structs in other programs
using SET_SS_LEN, then passing them to libratbox, on
4.4BSD based systems.