MFC r259943:

Address some warnings which showed up on the userland version.
MFC r260257:

Fix several bugs in sctp_bindx():
* Set errno to EAFNOSUPPORT if an address is provided which is neither
  AF_INET nor AF_INET6.
* Don't modify the arguments.
* Don't smash the stack when provided with a non-zero port.
* Handle the case correctly where the first address provided is
  an IPv6 address.
MFC r262252:

Remove redundant code and fix a style error.