text: inet6_option_find()
  Synopsis:
  #include <netinet/in.h> int inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type);
  Arguments:
  - cmsg
  - A pointer to the cmsghdr structure that must have been initialized by inet6_option_init().
  - type
  - The type of option to search for. Either IPV6_HOPOPTS or IPV6_DSTOPTS. This type is stored in the cmsg_type member of the cmsghdr structure pointed to by *cmsgp.
  - tptrp
  - A pointer to a pointer to an 8-bit byte.
  Library:
  libsocket
  Use the -l socket option to qcc to link against this library.
  Description:
  This inet6_option_find() function is similar to inet6_option_next(). It however, lets the caller specify the option type to be searched for, instead of always returning the next option in the ancillary data object. The cmsg is a pointer to the cmsghdr structure of which cmsg_level equals IPPROTO_IPV6 and cmsg_type equals either IPV6_HOPOPTS or IPV6_DSTOPTS.
  The tptrp is a pointer to a pointer to an 8-bit byte that the function uses to remember its place in the ancillary data object each time the function is called.
  The first time you call this function for a given ancillary data object, you must set *tptrp must be set to NULL. This function starts searching for an option of the specified type beginning after the value of *tptrp pointer. with *tptrp pointing to the 8-bit option
  - The option was found.
  - -1 with *tptrp pointing to NULL
  - The option wasn't found.
  - -1 with *tptrp pointing to non-NULL
  - An error has occurred.