alternatively, we could define it in sys/socket.h since SO* is
reserved there, and tcp.h includes sys/socket.h in extensions mode.
note that SOL_TCP is simply wrong and it's only here for compatibility
with broken applications. the correct argument to pass for setting TCP
socket options is IPPROTO_TCP, which of course has the same value as
SOL_TCP but works everywhere.
based on linux headers add the missing MCAST_* options
under _GNU_SOURCE as they are not in the reserved namespace
(this api was originally specified by RFC 3678)
the old behavior of exposing nothing except plain ISO C can be
obtained by defining __STRICT_ANSI__ or using a compiler option (such
as -std=c99) that predefines it. the new default featureset is POSIX
with XSI plus _BSD_SOURCE. any explicit feature test macros will
inhibit the default.
installation docs have also been updated to reflect this change.
this one is for program(s|ers) who haven't heard of uint16_t and
uint32_t (which are obviously the correct types for use in such
situations, as they're the argument/return types for ntohs/htons and
ntohl/htonl).
